The Portuguese special one left Chelsea by mutual consent after a highly successful tenure at Stamford Bridge and was replaced by Israeli manager Avram Grant.

"Chelsea without Mourinho, that's a completely different team," Ronaldo told Austrian newspaper Heute on Wednesday.

"You can never write Chelsea off, but I have a feeling that this will not be a good season for them."

Chelsea's stuttering form in the Premiership leaves them in seventh place of the league table with 15 points, seven adrift of leaders Arsenal who have one game in hand.

Meanwhile, the former Sporting Lisbon winger is confident United have what it takes to win the UEFA Champions League title this season.

"Manchester United is the favorite. AC Milan, Barcelona, Real Madrid and Internazionale also have good chances."

"We want to reach the final at the very least. I am extremely ambitious and want to win every title," he added.