Jose Mourinho has told Manchester United to be inspired by Roger Federer and ignore concerns over the pitch in their Champions League meeting with Young Boys.

Mourinho will not risk Antonio Valencia due to concerns over the Swiss side's artificial surface, with the right-back having missed the start of the Premier League season with a knee injury.

He will sit out United's Group H opener at the Stade de Suisse on Wednesday, which could hand right-back Diogo Dalot his debut for the club.

And Mourinho opted to use an unexpected example in the form of tennis great Federer when discussing the pitch in his pre-match news conference.

"We decided not to bring Antonio because his knee is not a knee that needs an artificial pitch at all," Mourinho told a news conference. "So we brought [Luke] Shaw back into the squad, I told already he is playing tomorrow, and we have Diogo, [Ashley] Young and [Matteo] Darmian ready to play."

"I don't want to use that [the pitch], especially before the match, as a possible excuse for a not very good performance. Everyone knows its different but I had to say, I said last week in Geneva UEFA meetings we had, what can I say..."

"As an example, we're in Switzerland, home of one of the best ever tennis players, and I am pretty sure the big man [Federer] is not happy to play on such a surface, but he has to play and win. Everyone knows he has a favourite surface, but he has to win on the surfaces he is not in love with."

"We have to do it, but Antonio is the only one we need to protect with his clinical situation, apart from that we give everything and try to win."

Shaw will return to the United team after missing Saturday's Premier League win against Watford due to a head injury sustained on England duty.