Manchester United suffered a shock 2-1 defeat at Istanbul Basaksehir on Wednesday, the English side's first loss in three Champions League group matches and the Turkish champions' first victory in Europe's premier club competition.
United fell behind after 12 minutes when Edin Visca's long pass found Demba Ba in acres of space and the striker ran forward before finishing neatly past goalkeeper Dean Henderson.
Basaksehir doubled their lead five minutes before halftime after Deniz Turuc nicked the ball from Juan Mata and passed to Ba who set up Visca to score.
Anthony Martial's header two minutes later gave United hope but despite enjoying plenty of possession in the second half, they were unable to break down the Turkish side's disciplined defence.
"The performance wasn't good enough against a team that worked and ran and they hit us on the break a couple of times and scored two goals like sometimes you do in Europe when you don't defend well enough," United manager Ole Gunnar Solskjaer told reporters.
Basaksehir scored their first Champions League goals and clinched their first points in the competition on a historic night for the club.
"We played well in the first two games too, but finally we secured a win. This is a big result for us, we are really proud," Visca said.
United, who beat last season's runners-up Paris Saint-Germain and RB Leipzig in their first two games, top Group H with six points from three matches. RB Leipzig sit second in the group after their 2-1 victory over PSG, Thomas Tuchel's side sit in third and Basaksehir remain bottom.
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.
"We played against a lot of good individuals in a good team. They were well set up, well organised and we were not good enough. That's it."