On his return to the Manchester United side, Paul Pogba has been challenged by Jose Mourinho to show what he is capable of in Wednesday's Champions League trip to Valencia.

It is a sign of the French World Cup winner's fall from grace in a difficult season for United that Mourinho confirmed he will start among a much-changed side at the Mestalla with qualification for the last 16 already assured for the visitors.

Pogba has been dropped by Mourinho for United's last two Premier League games as a frosty relationship between the pair has sparked speculation over both mens' futures at United.

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“I'm looking for him to play well and to have a good impact in the game and a good impact in the team - a team with many players that don't have many miles in their legs,” said Mourinho on Monday.

“A team with some players that are not playing a lot, so I hope that people like Paul and a couple of others that are normally in the team and they have that number of miles that players need to be at that top level, I hope he can have a good impact on the team.”

However, Mourinho turned on reporters when asked why he has failed to get the best out of Pogba -- who cost United a then world record £89 million in 2016.

“I don't think your question goes in the direction of what I want to answer or listen (to),” Mourinho added. “I don't like your question.

“You can put the question from another direction, I don't like the direction.”

Mourinho named teenagers Mason Greenwood and James Garner among his squad that travelled to Spain.But the Portuguese coach confirmed neither would start.

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“The kids won't start the match. Garner will be on the bench, and Mason is the protection player, in case we have any injuries,” he added.

Manchester United has already stamped its ticket for the knockout stage, but the only question remains if it can finish top of the group.

Juventus is in pole position as a win at Young Boys would mean it goes through as group topper, regardless of the United result. But if Juve slip up in Berne, Jose Mourinho's side will top the group with a victory in Valencia.

If Juventus draws against Young Boys, United will have to win by a margin of two goals or more to top the group.