Jose Mourinho has dismissed Arsene Wenger's criticism of Juan Mata's proposed move from Chelsea to Manchester United.
Arsenal boss Wenger said the £37m move raises questions about the fairness of the January transfer window.
"Wenger complaining is normal, because he always does," Mourinho said.
Chelsea lie two points behind Premier League leaders Arsenal and have played United twice, while United still have to face Arsenal and Manchester City.
Mourinho added: "Normally he should be very happy that Chelsea sold a player like Juan Mata, but this is also a little bit his nature."
Mata is expected to complete his move in the coming days, joining a United side that are 14 points adrift of the Gunners but who could still have a say in the destiny of the title.
Wenger had previously said: "Some teams have already played twice against one opponent and some others not.
"I can understand completely what Chelsea are doing. They could have sold him last week."
United travel to Arsenal on 12 February and will also welcome City to Old Trafford, but Mourinho was keen to shift focus to the fixture scheduling.
"When he says this is not fair, I think what is not fair is that his team always has the best days to play," said Mourinho. "This week, a week without midweek games, what everybody wants to do is to play earlier to have more time to rest for the next week.
"This is not fair, and when you go to the fixtures during the season, it's never fair, because they always get the right time to rest, the right time to play."
Both sides have FA Cup fourth round ties this weekend, with Arsenal facing Coventry at home on Friday night, while Chelsea meet Stoke on Sunday.