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.
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."