Roberto Martinez is a man of his word. Before Euro 2020, he promised he would sit with ESPN to do a long interview. After Belgium booked their place in the round of 16 -- they face Portugal on Sunday (stream LIVE on ABC/ESPN+, 3 p.m. ET) -- we talked for more than half an hour in which he dissected his team and reflected on the unique circumstances around this competition. He was smiling a lot too, because there is something special between the two of us, mostly because of the rivalry between France and Belgium.

When I wished him the best for the rest of the tournament, he rightly answered: "I am not sure you mean it, Juls!" Of course, he is right. Martinez is very often right.

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It's also fascinating to listen to him talk about football and about players. He and his Belgium squad have gone through so much in the past few months, and in the two weeks since the Euros officially kicked off. You can see in the way he talks about them how much he loves them and cares for them.

Above all else, Martinez, 47, is very attached to Belgium. The man from Catalonia has been the team's head coach for five years, replacing Marc Wilmots after Euro 2016, and has brought a new dynamic to the squad as well as a genuine structure to the whole operation. When he talks about Belgium as a country, he says "we." His commitment, passion and desire have inspired the team, and they now could be on the verge of greatness and of a first major trophy. If he delivers it, he will deserve a statue in Brussels, not far from the iconic Manneken Pis.

For now, they certainly approach the knockout stage with a lot of hunger and momentum. And ambition too, even if for him, England are the favourites to win it all. Before even thinking about the final, Martinez talks about some of his star players, the importance of a football DNA in your team, learning from past disappointments, the impact of fans returning to grounds and a very open tournament that's impossible to call...

Editor's Note: This interview has been lightly edited for clarity and length.

ESPN: Now that you've had a few days to reflect on the first part of the competition, what have you made of your team so far?

We have been together for 27 days now and the dynamics are really strong. The work of the players has been fantastic. We had to play in Saint Petersburg twice, and once in Copenhagen, and it's been a really good experience to be able to play in front of fans again.

Belgium were clinical against Russia, excellent in the second half against Denmark, after the entrance of Kevin De Bruyne, and in control against Finland. Do these performances satisfy you?

Yes. As you know, at international football level, it is very difficult to get a synchronised performance in which everyone has a real understanding of what we're trying to do. We got it and that has been really positive. You can see a real continuity in this group. We've been together for five years, and there's a real know-how within the squad -- that's always pleasing.

We were flexible with our approach for these games, and we looked like a proper team.

Your team seems to be going from strength to strength so far, too.

I agree with you. We are getting stronger. I think in any tournament, you actually have two tournaments in one. One is the group stage and you need to use those three games to make you better to get everyone ready. Then you have the knockout phases, which is a different tournament in itself. I agree with your analysis and the way we performed, but what's also important to me is that I was able to use 22 outfield players in these three games.

I think it is always important that everyone had their debut in the competition and got the emotion out of the way. Now, they are ready to help it in whatever way is needed, and I think that's a big plus and a big factor. It is really rare that the team that starts the tournament for you is the one that finishes it.

One of your key players so far, as expected, is Romelu Lukaku. But it's a different Lukaku than the one we usually see at the club level.

With Romelu, we always talk about his individual talent. He was born with this capacity for scoring goals and if you look, his stats reflect it. The number of goals he's scored for every team is quite exceptional. What we're talking about now, however, is a different player. Now we're talking about a player that, on top of his individual talent, has a real degree of maturity.

I know him well because I signed him for Everton at the age of 19, but these days he's a completely different human being and a different footballer. He can affect others. You can almost set different ways of pressing, different ways of playing, and he will execute them perfectly. And that has probably been the difference that I've seen in the last 12 to 13 months, and maybe a little bit longer.

Going to Inter was the perfect move, at the perfect time, with a perfect coach, with a perfect dream of winning the Serie A title, and I think that has developed Lukaku to a level that is, for me, the best in his career.

Does he still find ways to surprise you?

You need to see the way Lukaku started the tournament, with a real incisive play in his way of seeing the opposing goal, but then with the responsibility and the maturity in all the actions that you need to perform in that tactical set-up. For me -- and you know I am biased, Juls -- he is the best striker in the world.

Obviously, I understand that I worked with him every day, I see the way he commits himself to this profession. I see the way he always wants to improve. He always wants to listen, and that makes him a special footballer.

You could not play De Bruyne in the first group game because of his injury during the Champions League final. [De Bruyne suffered a fractured nose and eye socket in a collision with Chelsea defender Antonio Rudiger.] How did you feel when you saw him coming off that day?

It was a worrying time. The Champions League final arrived, and as you know, Kevin never comes off and never goes to the ground unless it is a big issue and on that day, to see him being taken off was heartbreaking. He'd been working hard for a long time to be in a game of that magnitude and unfortunately, he couldn't finish it. But it's been really nice to see that focus and desire to get back to full fitness, and to come back and help the team.

For me, De Bruyne is the best playmaker in world football. The capacity he has to read the game, to play with appreciation of time and space is unique and that's why I always felt that he is a candidate for the Ballon d'Or every season.

Did you ever doubt his return?

No. I'm delighted about the adversity he faced. I think he is a great example in life. Not everything goes according to plan and when you face adversity, it is how you face it and how you change it that matters. Kevin did that, and we're all benefiting from it now.

The adversity was intense for Axel Witsel, too, after he ruptured his Achilles ligaments in January. Yet you still called him up. It was a big gamble. Why is he so important for you?

There are certain positions where you have two or three players to choose from. Every national team has those. And then you have the players that, in the case of Axel, you can't replace. You can find other solutions, other partnerships or ways of playing, of course, but in Belgian football, you cannot replace Witsel like-for-like. It's because of his experience (over 100 caps), because of the way he plays and the incredible balance he gives you.

I don't consider calling him up to be was a risk because I could rely on his character. After he had surgery in January, he moved into a flat in Antwerp and just worked there for three sessions a day to recover. It's been a long and lonely five months for him. But if he's back so quickly, it is because he worked so hard.

I had no doubt that Witsel would be ready. What I never expected to see was him to be ready so quickly, because for him to play against Denmark was never on the cards. It is just that he progressed so well. Axel's character made my decision to take him to the Euros very easy.

You had another long-term injury with Eden Hazard. But he also looks fit now. You must be relieved?

It's been a process with Eden. I must admit that I was worried about him because he wasn't enjoying his life. His body was not reacting the way it had reacted over the past 15 years, and that's difficult. When you're an injury prone player, you are used to having to cope with a body that could break down at any time. But that's not Eden. He never had injury concerns when he was playing in France. He missed only 20 games in eight seasons in the Premier League, one of the most demanding physically League in the world.

When I saw Eden last March, he was very sad and down. And from that point, I think he started to work with a real incentive of becoming happy again and probably with the timings, we've been lucky.

Is he happy again?

Against Finland was the first time I've seen Eden happy and enjoying his football for a long while. And when Eden is happy, we are a much better team. November, 2019 was the last time he played 90 minutes for the national team, so you can imagine we had to wait a long time.

We saw in the game against Denmark that you struggled in the first half especially because of the fans. Why?

First of all, you need to understand that it was the first time we played in front of a full crowd for 14 months. Footballers are creatures of habit, and it's almost like we got shocked because the momentum was exceptional in the Denmark match. I thought the crowd built chemistry with their whole team, which allowed them to take extra risks and to be able to push that extra yard. They stopped us from playing and we found it very, very difficult to be ourselves. However, we had to show real resilience, because we made an early mistake and we conceded a goal.

I've seen [45-minute halves] like this many times. One goal becomes two and three goals and before you know it, when you want to react, it is too late. So it's a real positive lesson that we got out of that first half, but you remember it is a complete game. It's true that Denmark were better than us in the first half. We were better in the second half, but overall we were better because we won the game.

How did you experience Christian Eriksen's cardiac arrest?

If I can paint the picture a little bit, we were all watching the game together, Denmark vs. Finland, from St Petersburg as we prepared for our match against Russia. And five minutes before our meeting is the moment when Christian collapsed.

Everyone was shaken. The last thing you wanted to do then was to speak about football and about how to win a football match. It was so hard. The feelings were really strong. I must admit that we were just focusing on trying to get good news. All we did was just wait to hear that Christian had responded well to treatment. We were relieved when it came through to us that he was ok. Until that point, it was all very uncertain.

Then you saw a wonderful message, which was: Christian Eriksen is football, his life is football and he was doing what he loves. He was lucky that he was playing and that he collapsed during a football game, where he got all the help and care he needed, because had it happened while he was at the park playing with the kids, he might not have had that help. So it was good to see that the medical protocol worked so well and he was saved by doing the thing that he loves the most. He brought football together.

The way you turned the game around against the Danes in that second game must have made you happy?

For me, Denmark was a game we needed. It was a game that allowed us to react, to show our best side and face adversity in the best way. We've learned that when you are not at your best, you can just hold the damage to a minimum because in our side, we always have enough talent to need very little to score goals.

We have to be able to react. You can never be perfect for 90 minutes. You can never expect to be dominant for the whole 90 minutes because you play against international footballers and against other teams who want to win in the same way. What matters, though, is that over the course of the 90 minutes, you find solutions and you don't let the momentum hurt you too much.

We were not surprised by Denmark's victory over Russia because the momentum that the home crowd can create is very impressive. We saw it with Hungary as well. The majority of the players have been shocked with that difference of having a crowd. We haven't seen that for a long, long time.

Do the players have to adapt again now that fans are coming back into the stadiums?

Absolutely. Playing in empty stadiums was very different and I think as a player, you had to focus on yourself and find that inner motivation to be 100% in every action. Then, obviously, the communication became a big strength because you could hear everyone. You could just be coached directly at any moment of the game.

Now, all the sudden we've gone back to having full crowds. The communication is a lot harder, you need to pass the messages in a different way. You need to understand as a team and as a player the effect that the crowd can play in both penalty areas. I think that adaptation period will be very significant in this tournament. You've got teams that play three games at home in the group stages: England could play six of seven games at Wembley [if they reach the final]. That makes it a really different journey.

Which other team has impressed you?

Many teams have been impressive. If I had to highlight one, it would be Italy because they use that whole momentum in a very good way. We were talking about the effect of the home crowd, and playing [their group games] in Rome has been really important for them. Roberto Mancini has been working long enough with this team and you can see that they work like a club team.

Now, we're going to find out more about every team. There is going to be a lot of twists and turns. There is going to be big performances and low performances depending on where you play, if you're in a neutral venue or in front of your fans. I think we are going to get a very inconsistent tournament from this point on.

And a very open one?

Absolutely. England, for me, are still the big favourites. They are playing every game at home. You know that when the games are tight in the knockout phase, it's a big advantage to play at home. After that, on the day, a lot of small factors will be decisive in deciding the game. I don't think this is a tournament that you can predict. I think that it is a tournament where you need to see which team is more prepared to expect the unexpected and for that reason, I think, it's very difficult to call.

France and Belgium can meet again in the semifinal, like they did in 2018. Is there a feeling of revenge among you and your players?

Not necessarily. I know that obviously from the outside, it may look that way. I think we're just desperate to use that 2018 semifinal to our advantage. Not because it was France, but I think every time you lose a semifinal or a big game in a major tournament, it makes you a different team. France are the team that they are now because they lost the 2016 Euro final against Portugal in Paris.

We are a different team after losing that 2018 semifinal, too. We're looking to try to beat that feeling. Not necessarily against France. We want to learn from that semifinal to become a better team, and I think the feelings we had that night will help us in this tournament.

Do you feel you need to change your approach to beat teams like France? To be more efficient, maybe, and less of a free-flowing team?

We need to be very firm with what we believe. The DNA of this Belgium generation is the individual talent. We want to exploit this talent by taking risks, having the ball and being an attacking team. I don't believe that a certain style of play helps you to win games. I think, being very, very good in your style helps you to win games and I think that's what we are trying to do, trying to become better on the ball and off the ball.

I don't think we want to lose the identity of this generation because I do feel that this generation is going to affect the next generations to come in Belgium football. We are a small nation of 11 million people: we need to work with a very clear vision, and the vision is to have a very important DNA in our football. Whatever this generation does will have a big effect upon the future.

How much would winning this Euros mean to Belgium, to the players and to you?

Let's see. We have to beat Portugal in Sevilla first in the last 16. What do I always tell you? Always go game by game, step by step!