Manchester - Manchester United manager Jose Mourinho gave short shrift when quizzed on the possibility of a sensational return to Real Madrid as he prepares for a reunion with one of his old pupils, Cristiano Ronaldo, and Juventus in the Champions League on Tuesday.

A run of five games without a win has left Real boss Julen Lopetegui on the brink of the sack just four months after accepting the thankless task of replacing Zinedine Zidane at the Bernabeu after three straight Champions League titles.

Mourinho's future at United is also in doubt with the Red Devils languishing in 10th in the Premier League, nine points off rivals Manchester City and Liverpool, just nine games into the new season.

However, the Portuguese batted away a series of questions from Spanish and Italian journalists on whether a Real return would interest him at Old Trafford on Monday, highlighting that he signed an extended contract just this year till 2020.

"No, I'm happy here. I'm happy to see my contract out to the very last day of that contract and I would like to stay after my contract ends," said Mourinho. "All I'm thinking about is Manchester United."

Ronaldo is returning to Old Trafford for just the second time since he left United to join Madrid for a world record fee in 2009.

The five-time Ballon d'Or winner made his name in Manchester, but showed no mercy on his last visit when he and Mourinho teamed up to dump United out of the Champions League in 2013.

And Mourinho is well aware of the challenge he faces in setting up a defence that has conceded 16 times in the Premier League already this season to stop the top scorer in the Champions League for the past six seasons.

"He is one of the best players of all time," added Mourinho. "It's as simple as that."

After winning seven straight Italian titles, Juventus splashed €112 million on a 33-year-old Ronaldo to take them one step further in Europe and deliver a first Champions League title for 23 years.

And Mourinho believes Italian champions are the favourites to win this year's competition.

"For the last five years or so they've been real contenders to win the title. They've been to a couple of finals, they've won Scudetti on the trot and they have a really special player, who makes a real difference as well.

"As far as I'm concerned, Juventus are more than just a contender this season to win the Champions League."

Mourinho was encouraged by his side's second-half reaction in coming from behind in a 2-2 against Chelsea on Saturday, despite the disappointment of conceding a 96th-minute equaliser.

And Romelu Lukaku called on United to start games with the same intensity they have finished in recent weeks having also turned around a 2-0 deficit to beat Newcastle 3-2 before the international break.

"The first half we just started slow. No initiative on the ball and no movement," said the Belgian striker.

"Then in the second half we did everything we said we wanted to do in the first half. We do it always in the second half and that's why we come back to get great results.

"But now the key is to start games how we start them in the second half, and maintain it as much as we can."

Both sides have been dealt injury blows with Alexis Sanchez missing for United, while Juventus travelled without Sami Khedira and Mario Mandzukic.