Manchester United boss Ole Gunnar Solskjaer blasted "unforgivable" defending from his hapless side as they slumped to an embarrassing 2-1 Champions League defeat against Istanbul Basaksehir.
United started the game as firm favourites after an impressive win against Paris Saint-Germain and a 5-0 humbling of RB Leipzig.
But defeat in Turkey - a first-ever Champions League group-stage win for Basaksehir - heaps the pressure on the Norwegian boss, whose side looked short of inspiration and basic defensive nous in Istanbul.
The three-time European champions were badly exposed on the break as former Chelsea forward Demba Ba and Edin Visca gave the home team a two-goal cushion.
United gave themselves hope when they reduced the deficit shortly before half-time through an Anthony Martial header.
But despite multiple second-half changes and an array of attacking talent, Solskjaer's lacklustre team could not find a way past the organised Basaksehir defence.
Solskjaer said the performance against the hard-working Turkish side was not good enough.
"They scored two goals like you do in Europe when you do not defend well enough," he said.
"The first one is that we play a short corner and forget about the man up top. That is unforgivable. The second one as well, we are not very well organised to counter the press.
"You don't turn up and get three points in the Champions League," he added. "They are a team well organised and we were not good enough. That is it."
United, who have made a poor start to the Premier League season with three losses in their first six games, played poorly in the first half and although they showed greater urgency after the interval, they only managed one more effort on target.
Solskjaer sent on Paul Pogba and Edinson Cavani as substitutes and in stoppage time Alexandru Epureanu brilliantly cleared off the line to prevent an own goal as United's 18-match unbeaten away run in all competitions ended.
"We hoped we had enough to create chances, we just didn't. Emotions don't matter - when you lose, well you can think to yourself how we feel after we lose, that's not something we go out to do," Solskjaer said.
"They (two losses) have set us back a lot," said Solskjaer, whose team travel to Everton on Saturday. "You get a reality check every time you play a game of football."