Red Bull Salzburg 2-6 Bayern Munich
It was business as usual for Bayern Munich, who claimed an emphatic 6-2 triumph at RB Salzburg on Tuesday night.
The hosts took a surprising lead after just four minutes, with Mergim Berisha getting his first goal of the campaign.
Robert Lewandowski converted from the penalty spot to level matters in the 21st minute before Rasmus Kristensen's own goal completed the turnaround for the defending champions.
Masaya Okugawa restored parity for the hosts on 66 minutes, but four goals in the final 10 minutes from Jerome Boateng, Leroy Sane, Lewandowski and Lucas Hernandez handed Bayern the spoils.
Lokomotiv Moscow 1-1 Atletico Madrid
Atletico Madrid were denied a second win in the group stages after being held to a 1-1 draw by Lokomotiv Moscow.
Jose Gimenez put the visitors ahead on 18 minutes with a close-range header, but Anton Miranchuk's 25th penalty sealed a point for the Russian outfit.
Shakhtar Donestk 0-6 Borussia Monchengladbach
Borussia Monchengladbach surged to the top of Group B after a 6-0 mauling of Shakhtar Donetsk.
Alassane Pléa bagged a hat-trick on the night, while Lars Stindl, Ramy Bensebaini and an own goal from Valeriy Bondar sealed the rout.
Manchester City 3-0 Olympiakos
Manchester City made it three wins from three games in Group C with a 3-0 victory over Olympiakos.
Ferran Torres put City ahead on 12 minutes with his third goal in the group stages, before Gabriel Jesus and Joao Cancelo completed the win for Pep Guardiola's charge.
FC Porto 3-0 Olympique Marseille
FC Porto moved up to second in the group with a 3-0 triumph over Olympique Marseille.
First-half goals from Moussa Marega and Sergio Oliveira put the hosts two goals ahead, while Luis Diaz rounded off the scoring on 69 minutes.
Midtjylland 1-2 Ajax Amsterdam
Ajax Amsterdam secured the first win in Group D after seeing off Midtjylland in Denmark, despite having 11 players reportedly test positive for Covid-19.
Antony's first minute strike and Dusan Tadic's strike gave the Dutch giants a two-goal lead before 13 minutes.
Anders Dreyer pulled a goal back on 18 minutes for the hosts, but they were unable to find the equaliser.