Louis van Gaal has reiterated calls for the Premier League to introduce a break over the winter period in line with other leagues in Europe.
Germany's Bundesliga and La Liga in Spain are among a number of top flights that do not play over Christmas and New Year, when Premier League clubs are at their busiest in England.
When asked about the English clubs' exits from the Champions League and Europa League this season, the Manchester United manager said at his press conference: "We have to play four or five matches in two weeks and they have a break of two weeks.
"How many matches have Bayern Munich played in the meantime, for example? That's the difference. They are much fresher than players of Arsenal or Chelsea. That, in my opinion, is the difference because players need rest.
"Twenty years ago the English Premier League was up there, had a lot of money, a lot of players came to the Premier League because you are paying well and the Premier League is a high standard. But the other countries are developing themselves, and they also have a winter break."
Manchester United face Liverpool in the Premier League this weekend.