Manchester United boss Jose Mourinho has encouraged his players to follow the lead of tennis great Roger Federer.

There are some concerns about the artificial turf at the Young Boys' stadium, which is unusual for English teams to experience.

Players such as Antonio Valencia will not even take part in the game.

But Mourinho does not believe it can be used as an excuse for a poor result or performance.

"We decided not to bring Antonio because his knee is not a knee that needs an artificial pitch at all," Mourinho said in his press 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."