Manchester United captain Harry Maguire said an inability to defend, and not manager Ole Gunnar Solskjaer's tactics, is to blame for the Red Devils crashing out of the Champions League.
United required only a draw from Tuesday's trip to RB Leipzig to advance to the last 16 of the competition but were beaten 3-2 by last season's semi-finalists at the Red Bull Arena.
Solskjaer went with a five-man defence – a formation last used in the 2-1 win over Paris Saint-Germain in October – and United found themselves two goals down inside 13 minutes, both goals coming from simple crosses.
Only against Juventus in April 1999 have United been 2-0 down earlier in a Champions League match (11 minutes), with on-loan Manchester City defender Angelino scoring the first and setting up the second for Amadou Haidara.
Justin Kluivert added a third for Leipzig and, despite Bruno Fernandes scoring a penalty and substitute Paul Pogba heading in late on, the visitors fell short in Germany.
Maguire insisted the players have to take full responsibility for the defeat, which condemned United to Europa League football in the second half of the season, having reached the semi-finals of the competition last term.
"We started the game too slow," he told BT Sport. "It wasn't good enough. The first 20 minutes we weren't at it. They put two balls in the box and we failed to deal with them.
"We have to look at ourselves. We gave ourselves too much to do. You've seen how close we came at the end but we started too slow and we can't keep falling behind.
"We said on Saturday at half-time, 2-0 down, the next goal is crucial and we said it again tonight. They made it 3-0 and the task becomes even bigger.
"The third goal proved to be the crucial one but even three down we came close at the end. I don't want to look at excuses.
"We have to go out and be aggressive, win balls. That's the basics. If you can't defend crosses you're going to lose games. I don't want to look at shape - it's not an excuse."
Leipzig will join French champions PSG in the knockout stages, with United third and Istanbul Basaksehir fourth.
"It's a tough group but we felt we should get through," Maguire said. "That's the standards of this club.
"I'm gutted for everyone. We worked so hard to reach this competition last season. No matter what group we got it would be tough. We have to do more."
United have trailed in all five of their away Premier League games this season and gone on to win each of them, having rallied past West Ham 3-1 on Saturday.
3 - Man Utd have conceded 3+ goals in consecutive Champions League games for the first time since April 2003 (Both v Real Madrid). Whimper. pic.twitter.com/I2t38Iqjsy— OptaJoe (@OptaJoe) December 8, 2020
However, this latest European defeat has once again increased the pressure on Solskjaer and the Norwegian conceded his side are giving themselves too much to do.
"We started too late," he said. "We showed great spirit and come back again. It's different to the Premier League - you can't give a team a three-goal lead and expect to come back.
"We were unlucky towards the end and you almost thought it was in at the last minute there. Of course you can't say we were good enough, we weren't."
Solskjaer has lost six of his 10 Champions League games as United boss – the most of any manager in the competition after 10 matches while in charge of an English club.
And the under-fire United manager pinpointed last month's shambolic 2-1 away loss to Basaksehir as the turning point in his side's Group H campaign.
"It was a difficult group. The big defeat for us was the one away to Istanbul - that's where we lost the points we should have had," he said.
"Today we were close but we knew we had to defend crosses and balls into the box and we just couldn't clear them.
"As a footballer you can't feel sorry for yourself. You feel sorry for a few minutes tonight and then we focus on a massive game on Saturday."