He said: "United have spent a lot of money and again the question is how will they all click, coming into a team who are champions.

"Logically you expect them to be stronger and I think they will be. But there will be more competition for places and sometimes that can also take something away from the players."

Wenger also believes Fergie will be unable to placate the likes of Nani and Anderson - who played regularly for their former clubs - by insisting they are ones for the future. He said: "They are players for this season. They were both regulars for their teams in Portugal. They are not teenagers so if you are a special talent, you need to play at that age."

And Wenger reckons the arrival of £20m Owen Hargreaves will only deepen the conundrum faced by his opposite number at Old Trafford.

Wenger said: "I don't know where Hargreaves will fit in. Will he replace Michael Carrick? I don't think so because Carrick is a very good player. So I don't know how their best side will line up."