Bayern Munich forward Thomas Muller has said that playing in the Premier League is "very hard".
The 24-year-old Germany international believes that the lack of a winter break in England means that players are exhausted by the end of the season.
"It's very hard to be a professional footballer in England," The Mirror quotes him as saying. "You have many more games than we do in Germany and no break in the winter.
"Normally the body can regenerate by the time of a tournament, but the mental thing is harder to recover from.
"It's not easy for Mesut [Ozil] but I know how good he can be and I hope he has many good games for Arsenal."
Muller scored for Bayern as they defeated Arsenal 2-0 at the Emirates Stadium in the first leg of their Champions League last-16 tie on Wednesday.