United's management team are said to feel uneasy and overshadowed by his continual presence at the club.
Wenger, rejecting suggestions he is on the verge of retirement himself, said: "Ferguson was there for 27 years. When he appears in the stand the cameras are on him.
"It is what the players do on the pitch that wins you the games, not who is in the stand. It is as well not to go overboard.
"The problem is now, because United do not win all the games, the blame is pinned on Moyes.
"Sir Alex is the man who is missing but I think that is the wrong problem."
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