Bern (Switzerland) (AFP) – Jose Mourinho says Manchester United must not be left making excuses when they begin their Champions League campaign on Wednesday on a synthetic surface against Young Boys in Bern.

The Old Trafford club have been drawn in a tricky group along with Cristiano Ronaldo’s Juventus and Valencia, which makes starting out with a positive result at the Stade de Suisse all the more important.

But the Swiss champions’ artificial pitch will take some getting used to, and was the reason why United left Antonio Valencia behind.

“We decided not to bring Valencia because his knee is not a knee that needs an artificial pitch at all,” Mourinho told reporters in the Swiss capital on Tuesday.

“I don’t want to use that before the match as a possible excuse for a not very good performance,” he added of the surface, while insisting that he has already made his feelings on it clear to UEFA.

With a reference to Switzerland’s greatest sportsman, 20-times Grand Slam winner Roger Federer, Mourinho urged his team to just get on with it.

“We are in Switzerland, they have the best tennis player and I’m pretty sure the big man is not happy on certain surfaces, he has a favourite surface but he has to play. We’ll have to do it.”

United may have been European champions three times, but they come into this season’s continental campaign determined to make amends for a feeble exit from last season’s Champions League, when they were beaten by Sevilla in the last 16.

– Potential pitfalls –

Mourinho does not need to be reminded of the potential pitfalls of a visit to Switzerland, however.

Young Boys are Champions League group stage debutants, but their compatriots Basel have taken numerous English scalps in the competition this decade.

They beat United at home in the group stage last season, having also defeated Mourinho’s Chelsea in 2013. Basel also dumped Alex Ferguson’s United out in the group stage back in 2011-12.

Last season’s reverse did not prevent the Reds from progressing to the knockout rounds, though.

Mourinho said: “Yes I lost in Switzerland both matches but I won the group phase — a defeat tomorrow and I win the group, I sign immediately.”

It has been a troubled start to the season, but United come into this game on the back of successive Premier League wins over Burnley and Watford.

“We are improving, we found a certain balance in the team, especially in the competitive attitude,” the manager said.

“We are creating a lot of chances, we also find a way to protect ourselves in some specific situations, we managed to get the six points after two defeats which was very important, so I am happy.”

With a home game against Valencia next, United need a positive start in Group H, but Young Boys are unbeaten this season and will come into the match full of confidence.

Of his side’s European prospects, Mourinho added: “A team to win the Champions league needs to have fantastic quality in every part of the team and needs to go over certain matches.

“I think it’s very premature to talk about our chances when we have not played the first match.”

Young Boys won their first Swiss title last season since 1986 and finally made it through the qualifying rounds to reach the group stage at their sixth attempt.

Gerardo Seoane’s team are now hoping to make the most of home advantage after eliminating Dinamo Zagreb in the play-offs, although he brushed off suggestions the visitors might struggle on the pitch.

“These players have the quality to play on this surface, they have speed and great technique, so it won’t be a problem for the great players they have.”