The Red Devils' campaign got off to a disastrous start after the Swiss outfit struck a stoppage-time winner following Jesse Lingard's costly mistake, to claim a famous three points against the ten-man Premier League giants.
Cristiano Ronaldo got United's first with his third goal on his return to the club, but Aaron Wan-Bissaka's 35th minute sending off changed the game and Moumi Ngamaleu struck an equaliser before the game was flipped on its head late on.
Questions have once again been asked of Ole Gunnar Solskjaer's tactical nous following the defeat, with many criticising him for allowing the Swiss side to attack in numbers with his defensive substitutes - as well as his decision to take Ronaldo and Bruno Fernandes off the pitch in the second-half with the game locked at 1-1.
And O'Shea - who made 393 appearances for United, winning one Champions League crown and five Premier League titles - believes the artificial pitch did not help his former side's cause, despite admitting Wan-Bissaka deserved his sending off.
Asked whether he thought the full-back should have been served his marching orders, O'Shea told the talkSPORT Breakfast: "Yeah I do, unfortunately.
"He's taken that bad touch and slowed down and when you see the replay, I don't think anyone had any complaints over it.
"He's not tried to do the player but he's overstretched it and it looks really bad.
"That's a red these days but the pitch as well, I hated playing on those pitches," added O'Shea, who is surprised Young Boys' AstroTurf field is even allowed in Europe's elite competition.
"This is not about Man United losing last night, but I don't how those pitches are allowed in the Champions League - that's another story."
O'Shea also urged pundits not to jump to conclusions over the result, as he insisted United have plenty of time to turn things around.
Solskjaer declared ahead of the game that it was his aim to guide Manchester United to Champions League glory this term - which looks a laughable claim now after managing just two shots on target against a team that needed to go through the qualifying rounds to get the group stage.
"It's not an ideal start as you want the qualifying to get done as soon as possible as it could give you a chance to rest players towards the end of the group," the Irishman added.
"It's difficult one. Ultimately they'll be very disappointed with the result but there's plenty of time to recover it, that's the good thing."
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