Ole Gunnar Solskjaer, has admitted his team was lucky to beat West Ham 2-1 on Saturday.
Paul Pogba scored twice from the spot either side of Felipe Anderson’s finish, to give United all three points at Old Trafford.
However, the hosts were outplayed for most of the game and had controversial decisions go their way.
When the Hammers go through, they found goalkeeper David De Gea in inspired form.
Solskjaer feels his players had the Champions League quarter-final second leg at Barcelona next week on their minds.
“We got away with it, put it that way. It’s not easy because of Wednesday night and we made changes to the team, we got away with it: they deserved goals but we’re allowed to have a good goalkeeper. Manchester united manager says.
“Maybe the fact we have a game on Tuesday played on some of the player’s mind.
“I can’t understand why we play on Wednesday and then Tuesday and others play Tuesday then Wednesday, that’s my one little complaint to UEFA,” Solskjaer told Sky Sports.