Olympiakos clinched their first victory in the Champions League this season with a 3-1 win over Germany's Borussia Dortmund which kept them in contention for a last 16 spot.
The Greeks have three points while Dortmund, after a second defeat in three games, slumped to the foot of Group F which is now headed by Arsenal who have seven points while Marseille are on six points.
The Gunners defeated Marseille 1-0 in France.
Olympiakos, defeated by Marseille and Arsenal in their first two matches, were ahead against the run of play after just eight minutes.
Jose Holebas, a German player of Greek descent, headed Ivan Marcano's cross into the corner after beating Marcel Schmelzer to the ball.
But Dortmund, the champions in 1997, were level after 26 minutes.
Polish striker Robert Lewandowski, who had an earlier attempt ruled out for offside, volleyed past Franco Costanzo after Mario Goetze had set him up from a quick clearance from keeper Roman Weidenfeller.
Five minutes from the interval, Rafik Djebbour restored the Greeks' lead after a mistake by Mats Hummels.
A Kevin Mirallas cross evaded Hummels and Djebbour held off Neven Subotic to shoot past Weidenfeller.
As Dortmund pressed for a leveller in the second half, Olympiakos seized their opportunity when defender Francois Modesto headed in a free-kick from Ariel Ibagaza in the 79th minute to put the result beyond doubt.