This might not be the great Spain team of a decade ago, but the class of 2021 are not going away easily.

At risk of going home early after opening their Euro 2020 campaign with two limp draws, Luis Enrique's side produced a 5-0 win over Slovakia to book their place in the knockout rounds. Pitched against Croatia, the 2018 World Cup runner-ups, in the last 16, they went behind thanks to a bizarre own goal; recovered to go 3-1 up; conceded twice in the final 10 minutes, ensuring extra time; and then had to win the game all over again.

Euro 2020: News and features | Fixtures and bracket | Standings | Squads | Live on ESPN | VAR watch | Pick 'em

After 120 minutes of chaos, Spain ultimately won 5-3 and will face either France or Switzerland in the quarterfinals in St. Petersburg on Saturday. Victory in Copenhagen's Parken Stadium was their first success in a knockout game at a major tournament since the final of Euro 2012, completing a hat trick of trophies after success at Euro 2008 and the World Cup in 2010.

This version of Spain might not have the talent of those teams but they are not short of character. On this day, it was embodied by goalkeeper Unai Simon and striker Alvaro Morata in particular.

It was Simon's horrendous error which led to Pedri scoring a barely believable 40-yard own goal to give Croatia the lead. Then, with the score at 3-3 in extra time, the Athletic Bilbao goalkeeper pulled off a spectacular save to deny Andrej Kramaric.

Morata, meanwhile, has been the subject of death threats after his early performances this summer and despite missing an early header from point-blank range, it was his clinical finish after a wonderful first touch which put Spain 4-3 up.

Enrique has at times appeared to be the only one who thinks Morata should be playing as Spain's first-choice centre-forward, but his confidence was repaid with an all-round display which went some way to explaining why clubs all over Europe have shelled out a combined £170 million for his services.

"It's true I've been through things I haven't liked, but the majority of Spain is with me," Morata said afterwards. "The goal is for my wife, my kids and all the people who support me. You have to suffer to experience moments like that."

A team criticised for not having the end product their build-up deserved has now become the first in the history of the European Championships to score five goals in back-to-back games.

"We had chances to finish the game off quite early on but we showed character throughout," said Sergio Busquets afterwards. "When Croatia changed their system, they flooded the pitch high up and we didn't adjust quickly enough. Unfortunately, we didn't quite make it 4-1 before their fightback.

"But overall I'm so content with the result, how we handled the extra time and the fact that we are in the quarterfinals.

"Unai Simon knows he's got our total confidence. The goal was bad luck but his mentality is very laid back while remaining ambitious, and he showed that today.

He was ultra-secure after the goal and made some top saves."

This is still a Spain caught between eras and while there plenty of issues for Enrique to solve before travelling to Russia for the next round -- not least how his team managed to go from leading 3-1 on 85 minutes to needing extra time to finally see off Croatia -- he can be content that he looks to be laying the foundations for another cycle of success.

Barcelona midfielder Pedri, still only 18, was excellent in helping Spain reach the brink of victory in normal time while Ferran Torres was impressive in his role on the wing, getting a goal and an assist. The 21-year-old showed glimpses of his ability in his first season at Manchester City and should only get better. Eric Garcia, only 20, started at centre-back and after limited opportunities at Manchester City, his move to Barcelona should accelerate his development.

Enrique hasn't just put his faith in youngsters, though, and his decision to bring back Cesar Azpilicueta has proven to be a masterstroke. The 31-year-old Chelsea defender made his debut in 2013 but hadn't played for Spain since November 2018 before the tournament. Back in favour, he scored his first international goal to put Spain 2-1 on this day and also kept Josko Gvardiol quiet after the Croatia full-back caused so many problems for Scotland in their final group game.

"We had to suffer there," said Azpilicueta. "It's been a few tournaments since we went through a knockout match but today we broke the ice against the World Cup runners-up. It wasn't great to be scored against twice late in normal time but we were the better team in extra time and we deserve to go through."

Hit by Covid-19 during their preparations and finishing second in Group E behind Sweden to end up in the tougher side of the draw, Spain aren't doing things the easy way at Euro 2020. They seemed desperate to make it difficult for themselves against Croatia, too, but by the end of the week they will be one of only eight teams left.

Quite simply, Enrique's men are refusing to go away.