The former central defender, speaking at the Laureus World Sports Awards, is delighted with the job Grant has done.
"Everybody loved Jose Mourinho," he said.
"Grant is a very different person, he doesn't have the face of Mourinho but he is effective. He managed to win the players over and this is something I applaud him for, because it wasn't easy. He was lucky he had such professional players.
"They have helped him to build another attitude.
"Grant will be a real hero when he wins the Champions League. He needs three or four years because that is the normal lifespan of a coach - forget about Ferguson and Wenger because they are special.
"Everybody is surprised how it has gone when you look at how the club did the press conference.
"He didn't know how many years' contract he had and it was terrible, but they have steadied the guy and we should give him time.
"People misunderstand (Roman) Abramovich. He really loves football and just because he has money we doubt his intentions. But he and the people around him know the story of football."