It's the moment we never thought would happen. After 149 games, 120 goals, 41 assists and four final wins with Barcelona, Lionel Messi is back in the Champions League for the 18th time, but with another club. The famous UEFA music will be the same, but that's pretty much it.

On Wednesday in Belgium, PSG will start their Argentine maestro for the first time since his arrival at the club and for the first time, Mauricio Pochettino will unleash his star studded front three of Messi, Neymar and Kylian Mbappe.

The trip to Club Brugge was always considered by Pochettino and his staff as the game in which the six-time Ballon d'Or winner should make his first start. Messi played 25 minutes away at Reims before the international break, with that club debut broadcasted in 208 countries around the world and watched by millions. He missed the home game against Clermont on Saturday due to the late fixtures in the South American World Cup qualifiers and the return to France, so history will always note that his first start for Paris came in the "Venice of the North."

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It's also a chance for Messi to revive his love story with the greatest club competition in the world. Not only is it the tournament in which he's enjoyed some of his most iconic moments -- the clinching goal in the final vs. Manchester United in 2009, the slaloming run-and-goal against Real Madrid in 2011, man of the match again in the final vs. Man United that year -- but it's also the competition he's been eager to win again, having not lifted the trophy since 2015. The past half-decade was full of disappointment and heartbreak for Messi and Barcelona; will his quest for a fifth title, level with long-time rival Cristiano Ronaldo, be more successful in Paris?

In private, Messi is said to be very excited about his new team's prospects this season. For a start, it's probably the best squad Messi has played in since the glory days of Pep Guardiola at Barcelona. The past few seasons, he's been scarred by some huge losses: the Liverpool remontada at Anfield, the 8-2 humiliation against Bayern Munich in Lisbon in 2020, and Mbappe's masterclass in PSG's 4-1 win over Messi's Barcelona at home last season. There will be much tougher games than this one -- including the next three group games, against Manchester City and RB Leipzig (twice) -- but this is a good way to start the campaign. PSG visited Club Brugge's Jan-Breydel stadium where PSG won 5-0 in 2019 thanks, in particular, to an incredible 18-minute hat-trick by Mbappe after he came off the bench in the second half.

Wednesday will, obviously, be an incredible moment, a chance for Pochettino to show off one of the best attacking lines ever seen in this game and, arguably, the first time PSG begin the competition as the overwhelming favourites. On paper, certainly, Messi has taken this team to the next level, but is it enough? The squad believes so.

While the likes of Bayern Munich, Manchester City and Chelsea will be big contenders, the recruitment in the summer (Georginio Wijnaldum, Messi, Gianluigi Donnarumma, Achraf Hakimi, Nuno Mendes, Sergio Ramos), the fact that Kylian Mbappe ended up staying despite Real Madrid's astronomical bids and Neymar's joy of being reunited with Messi has elevated confidence in Paris. There's also the blend of experience (Ramos, Messi) and young talent, the strength in depth and the fact that they're the only team to have reached the semifinals in the past two seasons -- no easy feat given the toughness of the Champions League beyond the knockout stages.

And of course, Messi, more than Neymar or Mbappé, is the X-Factor. With him in the team, anything is possible, every objective is reachable and every game winnable.

However, Pochettino won't have a full squad to call upon in midweek; Ramos and Marco Verratti are injured, while vital holding midfielder Idrissa Gueye is suspended. This is not a new issue for the former Tottenham coach: he's been forced to rotate and mix players a lot so far this season, which is nothing unusual for big clubs like Manchester City, Bayern Munich or Chelsea. With a target of a fully fit and available squad between now and Matchday 2, when PSG host Man City, that's when we'll finally get to see what this PSG is about, what formation Pochettino prefers, where Messi fits best, how the front three might click and whether or not they have the right balance between defense and attack that's so often difficult for top teams to manage.

While Pochettino is under immense pressure to deliver, for Messi, the fun starts now. After the best summer of his life with Argentina and the Copa America, after the sensational move to Paris and settling in there with his family, it's time for him to really get his season started with PSG.