Manchester United suffered a shock 2-1 defeat at Istanbul Basaksehir, 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 St Germain and RB Leipzig in their first two games, top Group H with six points from three matches and Basaksehir have three after their first victory in the competition.
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."
Chelsea coast off back of Werner brace
Chelsea eased to a 3-0 win over 10-man Rennes in the Champions League Group E, thanks to two first-half penalties hammered home by striker Timo Werner and a tap-in by Tammy Abraham.
The match swung the way of the Londoners with the two penalty decisions, which both went against Rennes defender Dalbert Henrique, on loan from Inter Milan.
The Brazilian was shown a second yellow card and sent off in the 40th minute, after a long VAR check, when the ball ricocheted from his calf to his arm, having earned his first caution for tripping Werner in the box after 10 minutes.
Werner converted both spot-kicks emphatically, taking the role of Chelsea's penalty-taker from Jorginho who missed two earlier this season.
"I am happy, I am happy Jorginho is cool with it. It is another point that speaks for our team, we are not selfish. We all go in one direction which is good," Werner told BT Sport.
Abraham made it 3-0 five minutes into the second half with a short-range finish, after an inch-perfect cross by Reece James.
The comfortable victory left Chelsea top of Group E, ahead of Sevilla of Spain on goal difference, with three of the six games played.
It also represented a fifth clean sheet in a row for the Blues, who appear to have fixed the defensive frailties that dogged them last season, and in the opening games of this campaign.
"We had a very good game today," Werner said. "Also good for me is we had one more player on the pitch and could control it from behind."
Chelsea goalkeeper Edouard Mendy, bought from Rennes in September to replace the out-of-form Kepa Arrizabalaga, had little to do against his former team mates, until the 84th minute when he parried a shot by Clement Grenier.
"OK, the referee gives the second penalty but I think the red card was tough because he didn't do it on purpose. We continued to work hard but that was tough for us," Rennes midfielder Benjamin Bourigeaud said.
Barcelona 2 by Dynamo Kyiv 1
Juventus 4 bt Ferencvaros 1
Dortmund 3 by Club Brugge 0
Sevilla 3 bt Krasnodar 2
RB Leipzig 2 bt PSG 1
Zenit 1 drew with Lazio 1