The Portuguese, now in charge of Inter Milan, has witnessed what Sir Alex Ferguson's side are capable of at first hand having seen his side draw 0-0 in Italy in the first leg of their UEFA Champions League last-16 tie last week.
United sit top of the league, four points clear of second-placed Chelsea with two games in hand, and it would take a mammoth loss of form for the Red Devils to not go on to claim their third straight league title.
The former Porto boss is confident new Chelsea chief Guus Hiddink can turn around the club's fortunes and admits they can apply pressure to United, but feels the champions will reign again.
"Guus got off to a great start and I think he will guide Chelsea to many wins," Mourinho told Zoo magazine.
"Of course they can win it, but you'd think United are just too far in front. You never know in football, but I think United will be champions."
Mourinho renews his battle with Ferguson next week when he takes his side to Old Trafford for the decisive second leg.
The Inter boss has claimed that his side have nothing to fear as he feels they are the best team in Europe.
Belief"I think it is Inter, but Barcelona and Manchester United are looking very strong in their domestic leagues as well," he added.
"The European Cup will tell us a lot about who is the strongest."
The 'Special One' also insists that, despite his failure to perform on the big stage, his striker Zlatan Ibrahimovic is currently the best player in the world.
"There are four standout players in the world; Zlatan Ibrahimovic, Cristiano Ronaldo, Lionel Messi and Kaka, and I have one of them - Zlatan," he said.
"At this moment in time, I think I have the best one of the four, the best player in the world."
Recent whispers in Italy claim that the 46-year-old still hankers after a return to Stamford Bridge, but the man himself is having none of it although he did admit to missing the club.
"I don't need to talk about other jobs," he declared.
"I still have a very big job to do here at Inter. I said Chelsea will always be dear to my heart but my future is in Italy with Inter.
"It is a great city (London), but I miss my friends at Chelsea and also the fans. We had a very special relationship."
Read the full article in ZOO magazine, out now