Ole Gunnar Solskjaer won his first game back as Molde manager, as his Norwegian side comprehensively beat Scottish champions Celtic 3-1.
Ronny Deila's side were 2-0 down before the break, courtesy of goals from Ola Kamara and Vegard Forren, before Kris Commons got a consolation goal after the break.
However, Molde restored their two-goal lead instantly, as Mohamed Elyounoussi wrapped up the victory.
Jurgen Klopp will have to wait until the weekend to claim his first win as Liverpool manager, after he saw his side come from a goal down to draw 1-1 with Rubin Kazan.
Marko Devic gave the Russian side a shock lead, before Emre Can equalised shortly before the break, not long after Kazan skipper Oleg Kuzmin saw red for a second bookable offence.
Villarreal cruised to a 4-0 victory over Dimano Minsk, as Cedric Bakambu grabbed himself a brace.
Napoli recorded a convincing 4-1 away victory over Midtjylland, as Manolo Gabbiadini scored twice, with Jose Callejon breaking the game's deadlock.
Leo Lacroix's 20th-minute strike was enough to seal all three points in their Group B encounter with Bordeaux.
Fenerbahce scored a last-minute winner, as Fernandao's strike snatched all three points away from Ajax.
Braga beat Marseille in a frantic finish to their Group F fixture, as Alan scored a last-minute winner shortly after Michy Batshuayi had originally equalised a minute earlier.
Michal Kucharczyk cancelled out Davy de Fauw's first-half opener, as Legia Warsaw share the spoils with Club Brugge.
Rapid Vienna held on to all three points as they beat Viktoria Plzen 3-2, with the home side having to come from behind to claim victory.
Ten-man Groningen came back to rescue a point, as Danny Hoesen scored a rebound from his own missed penalty attempt to cancel out Kevin Luckassen's late strike.
PAOK and FC Krasnodar shared the spoils in their Group C match but both sides got a man sent off in a heated finish.
Results in full (half-time scores in brackets): Bordeaux 0-1 Sion (0-1), Braga 3-2 Marseille (0-0), Fenerbahce 1-0 Ajax (0-0), Legia Warsaw 1-1 Club Brugge (0-1), Liberec 1-1 Groningen (0-0), Liverpool 1-1 Rubin Kazan (1-1), Midtjylland 1-4 Napoli (1-3), Molde 3-1 Celtic (2-0), PAOK 0-0 Krasnodar (0-0), Rapid Vienna 3-2 Viktoria Plzen (1-1), Villarreal 4-0 Dinamo Minsk (2-0).