Mourinho takes his Chelsea side to Old Trafford on Monday for an opportunity to strike an early blow in the Barclays Premier League title race.
The defending champions and the Blues are under new leadership this term, but Mourinho expects the same challenge he faced against Ferguson's United.
"There are things that we cannot change," Mourinho said.
"David has experience and he knows that he cannot change history. The history that Sir Alex did is there and it is there forever.
"Is that a problem for David? I don't think so. I think David doesn't want to be compared with Sir Alex.
"I think he's in the best moment of his career - maturity, experience, a big, big, big club, very good players. I think he's in a fantastic position and I think he's going to do very well.
"I hope he doesn't win everything and he will leave something for the others, but he's in fantastic condition."
Mourinho enjoyed a close relationship with Ferguson, who informed the Portuguese of his intention to retire before making the announcement public.
After being omnipresent at Old Trafford during Mourinho's time in management, now there will be a different face in the Old Trafford dugout.
Source: PA
Source: PA