Ole Gunnar Solskjaer was left delighted with a battling win on the road at Stamford Bridge on Monday night, but quickly turned his attention to scheduling frustrations.
United, who won a fractious affair 2-0 at Chelsea, will travel to Belgium to take on Club Brugge in the Europa League tomorrow night, with boss Solskjaer baffled to have had to play in the league just three days earlier.
"We have to work hard to recover now because we've got another game on Thursday," said Solskjaer.
"So thanks for the help, for all the recovery we get in Europe.
"I saw Jose Mourinho say something about that as well. We don't really get too much help to prepare for Europe.
"How we didn't play this game against Chelsea on Friday, Saturday, or at least Sunday, is beyond me.
"I don't like to complain, you know that. So we've got to get on with it."
Mateo Kovacic has challenged Chelsea to "wake up" and take charge of their battle for Champions League qualification.
The Blues could see Tottenham leapfrog them into the top four with a loss to their bitter rivals at Stamford Bridge on Saturday.
Chelsea held a six-point lead over Jose Mourinho's men after winning 2-0 in north London on December 22, but that gap has evaporated amid the Blues' patchy form.
But a ninth league loss of the campaign, thanks to Monday's home defeat by United, left midfielder Kovacic imploring the Stamford Bridge men to snap out of their malaise.
"We need to improve a lot because we have tough games ahead of us and we have to be focused," said Kovacic. "We know this match means a lot for us because Tottenham are close behind us so we need to prepare ourselves quite a lot to win this game at home.
"We are still fourth so we are still in a good position, but we need to wake up because they are right behind."