Inter Milan face Mourinho’s former club in the Champions League later this month.
He said: “Will Chelsea become European champions? Certainly.
“When? They’re nearly there. If not this year, then next year.
“As always, I hope Inter can go all the way in the competition, but that’s also difficult. You need a bit of luck at the right moments, but if we play like we did in some games we can beat Chelsea.
“On the day of the match I will stay cool, although I know it won’t be easy. I had a beautiful time there.
“I can’t forget that I’ll be playing against friends.”