Arsenal rolled over Lille and there was more misery for Manchester United.
Barcelona's 100 per cent start to the season was under threat down 1-0 to Galatasaray in Istanbul, but the Spanish champions rallied to a 4-1 win.
Bayern were in even more trouble against Viking, trailing 2-0 at halftime before Harry Kane turned the game around with two goals after the break. Luis Diaz looked to have completed the comeback, but a red card for Michael Olise and a 90th minute goal from Herman Haugen provided another twist.
Arsenal cruised to a 3-0 win at home over Lille and Atletico Madrid piled more pressure on United coach Michael Carrick with a 2-0 win at the Metropolitano.
Inter Milan fell to a surprise 4-3 home loss to Club Brugge, and Villarreal beat Napoli 3-1.
It's 10 straight wins for Barcelona after they maintained their perfect record in all competitions despite early trouble in Turkey.
Aleksey Batrakov gave Galatasaray the lead before his team had a second goal ruled out for a tight offside. Joao Cancelo's goal leveled the score just before halftime and it was all Barcelona after that with goals from Fermin Lopez, Anthony Gordon and Karim Adeyemi.
A bizarre sending-off for Olise paved the way for Norwegian team Viking to rescue a draw in their first Champions League home game since 1992.
Shortly after Bayern went ahead 3-2, Olise picked up two yellow cards in quick succession - the second for tossing the ball at opponent Zlatko Tripic while the referee was still booking him for his first foul.
Tripic then provided the cross that allowed Haugen to head in the equaliser in the 90th minute.
Defender Lisandro Martinez hit out at Manchester United's hierachy after the club extended its winless run to five games.
Carrick's team have won just two games in all competitions this term and fell to a fourth loss after goals from Pablo Barrios in the first minute and Ademola Lookman in the second half.
"I have to control myself a lot. But sometimes it's a reflection in the mirror of how is our club at the moment," Martinez said. "We did a fantastic season last season. And now we expect more from the top, to bring more players to compete because many teams bring many players as well."
In London, Bukayo Saka stepped off the bench to score a goal in Arsenal's 3-0 win over Lille.
Jurrien Timber had given Arsenal the lead in the 64th. Saka came on after 65 minutes and within two minutes set up at goal for Eberechi Eze. Four minutes later he was on the score sheet himself.
Inter was on the losing end of a seven-goal thriller against Brugge, which pulled off an upset in Milan.
Nicolo Tresoldi is emerging as one of the brightest prospects in Europe and he enhanced his reputation with a hat-trick for the Belgian visitors, while Lautaro Martinez scored twice for Inter.
Azerbaijani outsiders Sabah claimed their first win in the league phase of the competition by beating Slavia Prague 2-0 in Baku.The club was only founded nine years ago.
Sporting Lisbon also sealed a 2-0 win at Lens through goals from Luis Suarez and Issa Doumbia.
Brajan Gruda's first Champions League goal lifted Leipzig to a 1-0 win over PSV Eindhoven
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