But he admits Moyes needs to overcome his rocky start.
Saha said: "I have no doubt that Moyes will be a success at Manchester United - but there is also no doubt he is fighting against time.
"When you are in his position, it comes down to how long it will take to put his team together, find the right tactics and get the best out of them. He is driven by an obsession to develop players, and that is always a good basis for success.
"One thing which does not change, by moving from Everton to United, is his desire to win or the quality of his commitment. There was no fear in the man to start again, to build a new team.
"He is obsessed with working hard every day, working hard to improve the mentality of his players and every aspect of their game.
"To develop players, and make them the best they can be, you need to demand that of yourself. He is a tough manager - and that includes being tough on himself - and that is an asset for any club.
"United will benefit from that approach, and it may take time to gel, but I'm confident he will succeed."
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