Federico Valverde struck in stoppage time to give Real Madrid a dramatic 3-2 Champions League victory at AEK Athens on Wednesday, while Liverpool surrendered the lead twice in a 3-2 defeat at Fenerbahce.
Manchester City avoided the same fate at RB Leipzig, Erling Haaland's 78th-minute winner securing a 3-2 victory. Arsenal survived a late scare to beat Slavia Prague 2-1 and move third on 10 points.
Como were the night's big scorers, thrashing Lens 9-1 in an astonishing display in France to equal the biggest victory in the competition's history.
Real twice came from behind to maintain their perfect start and sit second on 12 points from four matches, behind Paris St Germain on goal difference.
AEK threatened from the outset and their early pressure was rewarded in the 12th minute when Aboubakary Koita cut inside and fired into the top corner from just inside the box.
Thibaut Courtois denied Luka Jovic before Jude Bellingham, who had an effort ruled out for offside in the 27th minute, equalised five minutes later with a deft backheel from Marc Cucurella's low cross.
Koita's driving run and pass set up Stavros Pilios to restore AEK's lead in the 75th minute, his low shot going through Courtois' legs.
Kylian Mbappe tapped in Denzel Dumfries' cross three minutes later before Valverde delivered the winner, leaving AEK 29th on three points.
LIVERPOOL'S WINNING START ENDS
Liverpool arrived in Istanbul with three wins from three but Vedat Muriqi's 79th-minute winner ended that run and earned Fenerbahce their first victory of the campaign.
Trey Nyoni opened the scoring in the 25th minute, meeting a defensive header with a low volley that deflected off Kojo Peprah Oppong and wrongfooted Fenerbahce keeper Ederson.
Mason Greenwood levelled four minutes later with a free kick that struck Jeremy Jacquet in the defensive wall and skidded past Alisson.
Substitutes Cody Gakpo and Alexander Isak combined to restore Liverpool's lead in the 69th minute. Gakpo exchanged passes with Kostas Tsimikas before reaching the byline and delivering a cross for Isak to power a close-range header past Ederson.
The advantage lasted four minutes. Following a short corner, N'Golo Kante crossed and Gakpo's glancing header diverted the ball away from Alisson, leaving Archie Brown to tap into an unguarded net at the far post.
Brown then supplied the winner, looping the ball into the box after a long throw was headed back to him. Surrounded by three Liverpool defenders, Muriqi somehow headed past Alisson, wrapping up a poor night for Liverpool's defence.
Andoni Iraola's side dropped to eighth with nine points, while Fenerbahce climbed to 19th on five.
HAALAND DELIVERS
Man City led through Castello Lukeba's 37th-minute own goal as he tried to clear Nico O'Reilly's cross, but Ridle Baku equalised four minutes after halftime.
Enzo Fernandez restored City's advantage in the 58th minute before Antonio Nusa levelled three minutes later. Elliot Anderson's run and low cross then found Haaland, who slid in to finish at the far post.
City are seventh on nine points, six points clear of Leipzig, who are in the elimination places.
First-half goals from Noni Madueke and Viktor Gyokeres put Arsenal in control in Prague. Wiktor Nowak punished Arsenal's failure to clear a cross in the final minute, but Slavia remained 34th on one point.
Cesc Fabregas's Como scored six second-half goals in France to beat Lens 9-1, with Anastasios Douvikas claiming a hat-trick and an assist as the Italian side followed their 4-1 victory over Manchester United with another emphatic performance.
The winning margin matched Liverpool and Real Madrid's 8-0 home victories against Besiktas and Malmo as they became only the second team after Bayern Munich to score nine goals in a game.
Como climbed to fourth on nine points. Nico Paz, Lucas da Cunha, Marc-Oliver Kempf, Mattia Liberali, Martin Baturina and Matteo Papaccioli joined Douvikas on the scoresheet, with Ruben Aguilar replying for Lens.
Porto collected their first points with a 4-1 home victory over Napoli. Scott McTominay cancelled out Jan Bednarek's opener before second-half goals from Gabri Veiga, Jakub Kiwior and a Samu Aghehowa penalty secured victory. Porto are 26th and Napoli 27th, both on three points.
Konstantinos Karetsas scored Borussia Dortmund's 72nd-minute winner in a 2-1 victory over Real Betis after Aitor Ruibal had cancelled out Fabio Silva's opener. Betis, whose winning start ended, are 11th on nine points, ahead of Dortmund in 12th.
Club Brugge won 2-1 at PSV through goals from Nicolo Tresoldi and Carlos Forbs either side of Kodai Sano's equaliser, while Viking Stavanger beat Sabah 4-1.

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