If the main overarching story of European soccer and the Champions League in the second decade of the 21st century is one of stratification and superclub separation, the first day of the 2017-18 Champions League proper was yet another short chapter that furthered the narrative.

Bayern Munich, Barcelona, PSG, Manchester United and Chelsea didn’t just claim victories as the Champions group stage kicked off on Tuesday. All five began their campaigns with routs.

The most rampant of the five wins was PSG’s over Celtic. A 5-0 victory featured at least a goal each for the three members of a new-look front line, Neymar, Kylian Mbappe and Edinson Cavani.

One of the five victories, however, might prove costly. And that’s where we’ll begin our first of 12 2017 Champions League group stage recaps:

Man United wins, but Pogba injured

Paul Pogba was forced to depart United’s 3-0 victory over FC Basel in the first half after lunging into a challenge:

Pogba immediately reached for his left hamstring, and was soon sitting upright on the rain-soaked Old Trafford pitch, in need of a substitute.

The extent of the injury remains to be determined, but Pogba was reportedly on crutches as he left the ground:

The crutches are likely precautionary to avoid any further strain on the hamstring, but the Frenchman will almost certainly miss Everton’s visit to Old Trafford this Sunday. The Red Devils then travel to Southampton the following Saturday, with a League Cup tie sandwiched in between the two Premier League games. CSKA Moscow is next up in the Champions League two weeks from Wednesday.

Pogba was replaced on Tuesday by Marouane Fellaini, and United altered its approach to account for the switch. It lofted the occasional long ball into the box, and pumped in crosses when opportunities arose. That’s how Fellaini broke the deadlock 10 minutes from halftime:

Romelu Lukaku doubled United’s lead in the second half, and the Red Devils, despite conceding some embarrassingly clear-cut chances, were never really troubled thereafter. Marcus Rashford added a third late on to add the Champions League to his long list of debut goals.

But if Pogba misses any significant amount of time, that one large negative from Tuesday’s match will outweigh any and all positives.

Neymar, Mbappe, PSG cruise

No European night at Celtic Park is ever a comfortable stroll. Unless, apparently, Neymar is the navigator. The Brazilian winger, playing his first Champions League match since a record-smashing €222 million move from Barcelona, opened the scoring in Glasgow:

He then set up Mbappe, who tallied a PSG Champions League debut goal of his own. It wasn’t exactly the most graceful of Neymar assists, but it’ll count all the same:

And Cavani, the one holdover in Paris from last season, made it three from the penalty spot. A couple late second-half knife twists, one from Cavani and one via an own goal, made it 5-0. Which, in a few ways, was a quite fitting end result.

PSG announced itself as a contender with surprising ease.

Messi finally beats Buffon

Barcelona-Juventus was the high-profile clash on Matchday 1, and it was a tight contest for 44 minutes. Then it was no contest. It ended 3-0 to Barca.

It also saw Lionel Messi, at long last, find a route past Gianluigi Buffon. The legendary Italian goalkeeper was rooted to the spot as Messi slid a quick-trigger left-footed shot into the far corner:

Messi tallied again for his 435th Barcelona goal in the 69th minute. That made it 3-0. Thirteen minutes earlier, Ivan Rakitic had made it two.

After a turbulent offseason, Barcelona appears to have steadied itself, and already has a sizable advantage at the top of Group D.

Chelsea hammers Qarabag

Up until kickoff on Tuesday, FK Qarabag was an incredible underdog story. But when the pregame anthem concluded and the referee’s whistle blew at Stamford Bridge, the Azerbaijani side, making its Champions League debut, realized it was in for a rude awakening.

Pedro put the Premier League champions a goal up inside five minutes:

Not to be outdone, new signing Davide Zappacosta scored from improbable range 15 minutes later:

Qarabag was completely overmatched. The final scoreline, 6-0, was actually a quite fair representation of the game. It was as one-sided as Champions League games come.

Elsewhere, Bayern Munich notched a relatively uneventful win, and Roma-Atletico Madrid, the soccer hipster game of the day, ended in a stalemate. Here are the rest of the scores:

Other scores

Bayern Munich 3-0 Anderlecht
Roma 0-0 Atletico Madrid
Olympiacos 2-3 Sporting CP
Benfica 1-2 CSKA Moscow

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Henry Bushnell covers soccer – the U.S. national teams, the Premier League, and much, much more – for FC Yahoo and Yahoo Sports. Have a tip? Question? Comment? Email him at henrydbushnell@gmail.com or follow him on Twitter @HenryBushnell.