Manchester United boss Ole Gunnar Solskjaer hit out at the Champions League scheduling after victory over West Ham.
Solskjaer felt their poor performance was due to thoughts on their trip to Barcelona on Tuesday.
He said, "Maybe the fact that we have a game on Tuesday night played on some players' minds, but it shouldn't do.
"What I don't really understand is why we played Wednesday and then Tuesday [in the Champions League], and why other teams play Tuesday and then Wednesday. It's difficult to work it out, but we've got three points."
He added: "I'm looking forward to a better performance [on Tuesday night] and everyone knows we've got a way to go and we have to perform better, because if that was Barca today it would have been 5-0 [to them]."