Federer, a 20-times Grand Slam champion, has won tournaments on every playing surface in his sport, and Mourinho spoke of his admiration for the Swiss player's adaptability.
Captain Antonio Valencia will not play for Manchester United due to the artificial turf at the Stade de Suisse.
Luke Shaw was not in the squad Watford on Saturday after suffering concussion on worldwide duty earlier this month and the full-back may well miss out again in Switzerland, although he has at least travelled.
Marcus Rashford's future has been a hot topic over the last few days, with Jose Mourinho defending his handling of the youngsters' development.
"I don't want to use that, especially before the match, as a possible excuse for a not very good performance", Mourinho said of the pitch. He has a favourite surface but he has to win on the surfaces he is not in love with. "Apart from that, we go with everything we can, and we have to try to win".
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.
Trump economic adviser says USA wants serious trade talks with China
Since April, as the trade tensions began escalating, the yuan has depreciated against the U.S. dollar by nearly 9.5 per cent. FILE PHOTO - Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., September 12, 2018.
Paul Pogba seemed to suggest the plastic pitch was like a return to kind of areas he played on growing up as United prepared for the match without Jesse Lingard, Phil Jones, Marcos Rojo and Valencia.
"Having the flexibility to play multiple positions is an asset and Rashford can play off the left, off the right, probably even as a number 10 and definitely as a number nine".
Mourinho has described the artificial pitch in Bern as a "huge advantage" for Young Boys.
Manchester United 4, Young Boys.
Here are three players who Mourinho has to start on Wednesday night.
Marcus Rashford is line to start, meanwhile, with the striker set to accompany Romelu Lukaku in attack.
The two-time Champions League victor believes football has evolved beyond the days of players being pigeon-holed in one position and Rashford's versatility is an added string to his bow.