Robert Lewandowski:
This wasn't the homecoming he dreamed about.
Lewandowski was all smiles before the match, greeting his former team-mates in the tunnel. He embraced Manuel Neuer, Thomas Muller and Joshua Kimmich, players who stood alongside him as he became arguably the best in the world.
But, playing in his former home, Lewandowski didn't look like the best in the world. Instead, he looked oddly human.
Lewandowski was uncharacteristically wasteful, even if he was as dominant as usual when it came to chance creation.
Chances were missed and moments were wasted, as Lewandowski and Barcelona were never able to seize control of the game, even if they should have.
Marcos Alonso:
For 45 minutes, Alonso demonstrated exactly why Barcelona signed him from Chelsea. He looked like the stopgap everyone expected to be, an exceptional left-back to bridge the gap from Jordi Alba to the next generation.
One moment of negligence doesn't lose him that status, but it did contribute to Barcelona losing the game.
It was a mental lapse that those that follow Chelsea would be familiar with. With the game still scoreless after a strong Barcelona first half, Alonso completely turned off for a set piece.
Lucas Hernandez dashed in, and Alonso was left defending no one. Completely free with his header, it was an easy finish for the French World Cup winner.
Ousmane Dembele:
Dembele has played himself into a different stratosphere this year, becoming one of the most dangerous wingers in the world. Becuse of that, the expectations are now higher.
World-class wingers aren't allowed to be as wasteful as Dembele was because, wow, was he wasteful. Dembele gave the ball away time and time again as Barcelona's attack lacked the needed edge in the final third.
Raphinha, Ansu Fati, Ferran Torres... Barcelona can survive a day when they aren't at their best. But, at this point, they can't win these big games unless Dembele is an absolute killer, and he simply wasn't on Tuesday night.