Manchester United captain Harry Maguire said the decision to switch to a back three at half-time against Young Boys was as a result of the crosses the home side were putting into the box.
United led 1-0 at half-time against the Swiss side but had played with 10 men for the final 10 minutes of the first half after Aaron Wan-Bissaka had been shown a straight red card for a foul on Christopher Martins.
In that time United had to deal with a bombardment for the wings, which led to Ole Gunnar Solskjaer introducing Raphael Varane at half-time in place of Donny van de Beek.
That meant Varane lined up in the centre of a back three, with Victor Lindelof on the right and Maguire on the left. But the home side equalised through Moumi Ngamaleu and then landed a 95th-minute winner after Jordan Siebatcheu pounced on Jesse Lingard's weak backpass.
“We started the second half well, I think the shape helped us defend crosses a lot better, you saw towards the end of the first half they put a lot of numbers in the box and with a back four we couldn’t really control the box very well," Maguire told MUTV.
“The shape worked really well, it’s two goals we’ve conceded and not really any major chances, a few long-range shots and crosses across our goal which you expect with 10 men.
“We could have been more of a threat on the counter-attack, but it’s disappointing to take."
United had taken the lead in Bern through Cristiano Ronaldo's 13th-minute goal, but now face a challenge in the group ahead of Old Trafford fixtures against Villarreal and Atalanta.
“We put ourselves in a strong position, it was a tough game, a tough surface, away from home we found ourselves down to 10 men, we looked comfortable in the game, we conceded a scruffy goal, it was really unlucky." said Maguire.
“We weren’t playing our greatest football, we weren’t the biggest threat at the other end of the pitch, we looked really solid, we didn’t concede too many chances and then the big sucked punch at the end.
“It’s the first game in the group, we’ve got many games to bounce back and we must do."
