United make their return to the competition on Tuesday night when Swiss champions Basel visit Old Trafford.

On the eve of the tournament, Mourinho insists there are "four or five" teams with a real possibility of lifting the trophy in Kiev in May -- among the likes of Real Madrid, Barcelona, Bayern Munich and Paris Saint-Germain.

But for the United manager, he is simply focusing on getting out of Group A ahead of Basel, Benfica and CSKA Moscow.

He told a news conference on Monday: "I think in the Champions League there are four or five teams with an incredible level of quality and experience and know how and that's what makes the difference.

"Apart from that there many teams in Champions League who are very similar to teams in the Europa League.

"Feyenoord and Anderlecht were in the Europa League last season and are champions in their countries and now playing in the Champions League.

"We have to try to qualify and go to the last 16 and enjoy that special knockout phase with the best teams in Europe."

Mourinho could be without Marouane Fellaini for Basel's visit after the midfielder missed the 2-2 draw with Stoke with a calf injury.

Fellaini trained with the squad at Carrington on Monday. But Mourinho insists it will be a blow if the Belgian is not fit to play for a second game in a row.

"He's a very important player for me, much more important than what you can imagine," Mourinho said.

"I feel weaker without Fellaini in my squad, it doesn't matter if he is in team or the bench so if his condition is improved I will select him but I cannot say yet."

Mourinho suggested Fellaini had picked up the injury before the international break and seemed unimpressed he played 89 minutes for Belgium against Greece before being ruled out of the trip to Stoke.

He said: "He had a problem, played the match against Greece and after the match felt the problem. When players go to the national team they belong to the national team."

Mourinho is set to field Victor Lindelof and Chris Smalling against Basel with both Eric Bailly and Phil Jones suspended.

Lindelof has not played in the Premier League since his £31 million move from Benfica in the summer and Mourinho has suggested the Swede may be more suited to games in Europe.

He added: "I think it's easier for him to play Champions League, it's more comparable to the Portuguese style of football, to the football in the Portuguese League.

"There is more difference in relation to the Premier League. There is no need to adapt to the Champions League. He needs a bit more time to adapt to the Premier League, especially the new Premier League.

"He's an intelligent kid, very bright, very clam, he knows step by step he is going to be there. But for Basel I know he is more than confident and I am more than confident.

"He is a kid with a lot of potential, trust me. There is reason for the others, Eric and Phil, to be worried because he is a very good player."