He added: "I don't want to use the pitch, especially before the match, as a possible excuse for a not very good performance".
With a reference to Switzerland's greatest sportsman, 20-times Grand Slam victor Roger Federer, Mourinho urged his team to just get on with it.
"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. We'll have to do it".
Mourinho has been the subject of criticism for stunting Rashford's progress in the Manchester United team over the past few seasons.
Mourinho does not need to be reminded of the potential pitfalls of a visit to Switzerland, however.
Young Boys are, at this stage, something of an unknown prodigy, and unexperienced at this level: they will not like the sight of Shaw running at them full pelt.
Marcus Rashford's future has been a hot topic over the last few days, with Jose Mourinho defending his handling of the youngsters' development. Both losses came against FC Basel in 2011 and 2017.
Mourinho has described the artificial pitch in Bern as a "huge advantage" for Young Boys.
The 20-year-old managed just one Manchester United start, playing a total of 122 Premier League minutes, before being England's match-winner twice during the worldwide break.
"I would focus on the first match, and after that on the group phase, one of the most hard group phases, and we have two positions to qualify and our focus must be on that".
Man Utd have had a mixed start to the new campaign as they recovered from consecutive defeats to Brighton and Tottenham by picking up vital away wins at Burnley and Watford in recent weeks so Mourinho will be hoping to build some momentum.
"Everybody knows it's different but what I had to say I told last week in Geneva in the UEFA meeting that we had and what can I say?"
"We have Lukaku, Rashford, Mata, Alexis, Martial - they all can not play together, so try to be a little bit happy for the ones that are playing and not be critical of the ones that are not".
Citing anonymous sources, the Washington Post and the Wall Street Journal reported that the tariffs would be set at 10%. This year, imports from China through July were up almost 9 percent from the same period of 2017, according to U.S.
It had hoped to strike a deal within a couple of months, but the process took much longer than expected, say reports. The Wall Street Journal first reported the sale. "A treasure trove of our history & culture".
The middle of the cone shows Florence coming ashore around Topsail Island - a slightly southern tweak from earlier projections. While Florence is expected to strengthen as it approaches the Carolina coast, the storm will weaken before it makes landfall.
He started with a sizzling pace and quickly shook off his biggest opponent, Wilson Kipsang , to make it a one-man race. He ran solo for the last 17 kilometres of the race after his pacemakers dropped out much earlier than expected.
The long-running NBC sketch show, already the top Emmy victor ever with 71, won again for best variety sketch series. No surprise there, as the veteran actor - best known for playing Fonzie in Happy Days - was a firm favourite.
In a recent interview with Collider , Phoenix promised that the new film defies the convention of a typical comic book movie. Phoenix, 43, has unkempt, collar-length hair and is wearing a rumpled, button-down shirt and jacket in the picture.
An estimated 2,975 people died in the Category 4 storm's aftermath when medical resources were strained beyond the breaking point. Roy Cooper and Wilmington, North Carolina, Mayor Bill Saffo to "just (let) them know, we know how it feels".
Trump has also complained about America's gaping trade deficit - $336 billion past year - with China, its biggest trading partner. And it was not under Bush", said Derek Scissors, a China expert at the American Enterprise Institute.
Thielen caught 12 passes for 131 yards and a touchdown, and Diggs had nine receptions for 128 yards and two touchdowns. According to referee Tony Corrente, the flag was thrown because Matthews "lifted him and drove him into the ground".
They are one of the best counter-attacking teams in Europe. "It will be a very tough opponent", said the Argentinian. Dele Alli is out for Spurs with a hamstring injury while Hugo Lloris is sidelined with a thigh problem.
Trump Claims Russia Campaign Probe Illegal
NBC's " Meet the Press " host Chuck Todd asked Schiff if Trump hired Manafort "without vetting him", in a haste to prevent Sen. Manafort, 69, entered the courtroom with a broad smile, wearing a dark suit and red tie, and mouthed a kiss to his wife.
'Dangerous' moon mission eases Musk's woes
SpaceX has announced the identity of its first passenger to fly on its forthcoming BFR spacecraft, headed around the moon in 2023. Before revealing Maezawa's mission to the Moon, Musk gave a heartfelt introduction as to why SpaceX exists in the first place.
Third strawberry brand recalled amid new threats
The Queensland Police Service said it was investigating the contamination relating to sewing needles inserted in strawberries. Meanwhile, a NSW mother revealed her ten-year-old child discovered sabotaged fruit in a case yet unconfirmed by police.
Predicted Chelsea Line Up vs Cardiff City
Ruben Loftus-Cheek is a doubt for the game with an injury, while Emerson and Davide Zappacosta are also unlikely to feature. The gap was 30 points at the beginning of the season.
Florence, a wet and unwanted visitor, besieges Carolinas
A state of emergency was declared in five coastal states - North Carolina, South Carolina, Georgia, Maryland and Virginia. The Miami-based center says Florence is bringing "catastrophic" fresh water flooding over a wide area of the Carolinas.
Davids warns Juventus, Barcelona: Pogba unconvincing
On Wednesday, Pogba further fueled rumors of his leaving when he said: "Who knows what will happen in the next few months". Pogba is now away on France duty and should feature in the Nations League clash with Netherlands in Paris on Sunday.