Arsene Wenger feels Manchester United's trip to the Middle East could have an impact on the title race.
United played a friendly game in Saudi Arabia last Monday before returning in time for the weekend's FA Cup tie with Tottenham Hotspur.
The Red Devils overcame Spurs 3-1 and will now play Wenger's Arsenal side in the fifth round of the competition next month.
Arsenal are slugging it out with United for this season's title and Wenger admits he would not copy his rivals' example of a mid-season friendly.
Wenger also believes that the focus of Sir Alex Ferguson's side could be affected by the winter jaunt to warmer climes.
"I have never done it," Wenger told reporters regarding United's trip.
"It can have a long-term impact, but in the short-term you can suffer in the next game as you travel, you come back, you need time to adjust and you switch off when you are away in a different country.
"So the focus could go a little bit and you can suffer in the next game."