He insisted compatriot Moyes will deliver similar success despite a shaky start to his tenure.
Law said: "He was the right choice. I thought very highly of him and what he did at Everton was fantastic.
"There's no doubt about it, he will be a successful manager. I can't predict the future, I don't have the crystal ball, but I just feel that he will be.
"He's a sensible, level-headed guy and if Sir Alex thinks he will do well, he will.
"To follow Ferguson is not an easy job and everybody has got an opinion. They go game-by-game and they don't look at the long-term in football."
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