Olympiacos are top of Champions League Group A after former Fulham midfielder Pajtim Kasami grabbed the winner in a 1-0 victory over Juventus.
The Greek champions are level on points with Atletico Madrid, who sit second after hammering Malmo 5-0 at the Vicente Calderon.
All the goals came in the second half as Koke, Mario Mandzukic, Antoine Griezmann, Diego Godin and Alessio Cerci secured a valuable three points for the Spanish champions.
Giulio Donati and Kyriakos Papadopoulos both scored in the second half as Bayer Leverkusen beat Zenit St Petersburg 2-0 to take charge of Group C.
Monaco climbed above Andre Villas-Boas' side into second place as they drew 0-0 with Benfica, who earned their first point of the campaign.
Borussia Dortmund hammered Galatasaray 4-0 away from home to make it three wins out of three in Group D.
Pierre-Emerick Aubameyang scored twice in 18 minutes for the visitors, first tapping home Marco Reus' pin-point pass before adding another from close range.
Reus put the Greek champions out of sight before half-time with a stunning, curling shot before substitute Adrian Ramos added a fourth late on.
Arsenal look to be joining Dortmund in the knock-out phase after two goals at the death secured a remarkable 2-1 win at Anderlecht.
Real Madrid delivered a first-half master-class to thrash Liverpool 3-0 at Anfield and go six points clear at the top of Group B.
Liverpool's chances of qualification are far from over, however, as fellow challengers Basel lost 1-0 at Ludogorets.
Basel's Serey Die was sent off in the 18th minute but the game looked to be heading for a goalless draw until defender Yordan Minev scored the decisive goal, meaning Ludogorets, Liverpool and Basel have three points each.
