What went wrong for Barcelona in their collapse against PSG?

It seems were going just a little too well for Barcelona.

Xavi's side played out of their collective skin to earn a 3-2 win away at Paris Saint-Germain in the first leg of their Champions League quarter-final last week. When they went 1-0 up on the night of the second leg, it seemed for all the world they would cruise through.

And then the implosion began. For once, PSG were present for a Champions League meltdown and they were instead the onlookers rather than the unfortunate protagonists.

How did it go so wrong for Barca? What led to them losing 4-1 on home soil?

A lack of discipline, clearly

Those of a Barcelona persuasion can try and convince themselves otherwise, but let's be honest with ourselves - Ronald Araujo's foul on Bradley Barcola was worthy of a red card. It was a daft challenge that didn't require him to make such a risk with the score as it was and with so much of the game left remaining. Just let Barcola through, for goodness sake!

But from there, Barcelona lost their heads. Every 50-50 decision seemed to against them, much to the ire of those draped in those famous Blaugrana colours inside their temporary Montjuic home.

In order to reach the semi-finals, all PSG had to do was remain calm. Their hosts were playing into their hands and the openings would follow.

Joao Cancelo's hideously stupid lunge on Ousmane Dembele led to Kylian Mbappe putting PSG in front in the tie from the penalty spot. PSG's clinching goal late on was a masterpiece of woeful defending on Barca's part, they at this point now frenzied and panicked to the point of no return - they were going down in flames one way or another.

The story would almost certainly have been different if Araujo had never been sent off. But he was. That's the reality Barcelona are struggling to come to terms with.

Xavi's emotions spilled over

There's only so much a team can do when they only have ten players on the pitch, and such a shortcoming in the Champions League was likely to be fatal.

It's been an extremely frustrating season for Xavi, who announced in January he would stand down from his post in the summer, citing fatigue and a lack of appreciation for his work.

Such grievances have taken their toll on Xavi. After being sent off early in the second half, he has now received more red cards as a manager (three) than he ever did as a player (two).

He's known for his over-enthusiastic touchline antics, but this was a night where his young team needed their leader to guide them through the storm, not add to the turbulence. It's similar to the accusations Mikel Arteta and his youthful Arsenal side have faced in the last couple of seasons.

It's not Xavi's fault Barca went out and he's unfortunate not to have woken up on Wednesday as a Champions League semi-finalist. They just ran out of steam and endeavoured to make lives worse for themselves.

Poor decisions and fine margins

The margins in the Champions League are oh so fine. At this stage of the competition, they're razor-thin.

Araujo and Cancelo's fouls were obviously on the opposite side of that line by a considerable distance, but Barcelona weren't too far from some incidents going their way.

Ilkay Gundogan rattled the outside of the post just after PSG levelled the aggregate score - that was unlucky. Robert Lewandowski spurned a great chance when he had runners other side of him only minutes before Mbappe iced the game - that was wrong.

With everything going on upstairs at Barcelona as well as their stacked injury list, it's a minor miracle they even got to the quarter-finals, really.

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