Ole Gunnar Solskjaer took responsibility for Manchester United's damaging Champions League exit on a night when his side "didn't turn up" until it was too late against RB Leipzig.
Things had gone awry after a stunning start to Group H but the Red Devils only needed a point at last season's semi-finalists - a side they beat 5-0 just six weeks ago - to secure progress to the knockout phase.
But Europa League football now awaits United having fallen just short of a remarkable European comeback at Leipzig, where Angelino, on loan from Manchester City, and Amadou Haidara scored within the opening 13 minutes.
Substitute Justin Kluivert added a third in the second half and it proved too big of a hole for Solskjaer's comeback kings to climb out of, with Bruno Fernandes and Paul Pogba scoring late goals in a galling 3-2 defeat.
"We didn't perform as a team well enough and that's always the manager's responsibility, to get everyone ready," the United boss said.
"We knew they were going to come at us, we knew they were going to put crosses in the box and unfortunately we conceded two goals and we never got going.
"In games earlier (this season) when we've conceded the first goal, we've played pretty well.
"Today we just didn't turn up until they scored the second goal. Suddenly then we started playing again.
"We had one chance maybe at 1-0 - Mason (Greenwood) had a good chance there - but after 2-0 we started playing.
"Second half was one-way traffic more or less and the one chance they had, they managed to score.
"So, 3-0 is going to be difficult but they all gave everything, very good character, effort. I can't fault anyone and we were close to getting the third.
"That would have been some achievement against a good team like Leipzig."
United put in a five-star display in the reverse fixture at Old Trafford in October, just a week after winning 2-1 at last season's runners-up Paris St Germain.
But the shock defeat at Istanbul Basaksehir ultimately proved a key moment in the group, as did the unwise decision to leave Fred walking a tightrope before his inevitable red card in last week's 3-1 home defeat to PSG.
United only needed a point from that match or this trip to Germany to reach the last 16, but failure to do so means an unwanted return to the Europa League awaits.
"We did everything we normally do in preparation," Solskjaer said, having dismissed suggestions that comments from Pogba's agent on the eve of the game were a distraction.
"With the video meetings, the training sessions, recovery with all the games we've got. Of course we know that everyone wants to be up for a game like this, everyone's ready for a game like this.
"The season we are playing and the demands on the players, sometimes it maybe takes them 10 or 15 minutes to get going.
"Today they scored two good goals. Maybe the referee should have done something with the second one with the push in Alex (Telles) back.
"Maybe we were not streetwise enough. Maybe he should have dropped and fallen on the floor because he gets pushed in the back.
"The first one is something that we prepared for and was not good enough.
"I think back and look at this season and look at the players and I actually admire them for being as ready as they are at times.
"Today it just didn't work for us. It is a difficult season, there are difficult circumstances this year and of course we were up for it and the character and effort I can't fault."
Tuesday's result means Leipzig progress to the last 16 at United's expense, much to the delight of coach Julian Nagelsmann.
"It was really intense at the end, but we played a good game for long spells," he said.
"The players implemented our plan well, especially in the first half.
"The boys fought hard. I said before the game that they are machines and they showed that again tonight."