Olympiakos opened their Champions League campaign with a 3-1 win away to Partizan Belgrade in the third qualifying round on Tuesday.
El Fardou Ben Nabouhane opened the scoring for the Greek giants in the sixth minute after a one-two with Marko Marin, only for Partizan to equalise four minutes later as a rebound came back off Tawamba's body and into the net.
But 10 minutes after the break Ben Nabouhane struck from distance to restore the lead, and Emmanuel Emenike was played through in stoppage time to seal it.
Fellow Greek side AEK Athens was less fortunate at home, losing 2-0 to CSKA Moscow, who got headers from Alan Dzagoev and Pontus Wernbloom.
Vardar continued their unlikely run by beating Copenhagen 1-0, a week after eliminating another Nordic side in Malmo.
Milan Skoda scored the only goal for Slavia Prague to win their home leg against BATE Borisov.
FCSB, the former Steaua Bucharest, erased a pair of deficits to draw 2-2 with Viktoria Plzen, while Qarabag and Sheriff Tiraspol shared a goalless draw.