Olympiakos advanced to the Champions League group stage Tuesday, winning 2-1 at Krasnodar for a 6-1 aggregate victory.
The Greek league runner-up will play in its 19th Champions League group-stage campaign.
Old rivals Red Star Belgrade and Dinamo Zagreb advanced also to the Champions League group stage after making it through their playoff second-leg games.
The former fierce domestic rivalry between the current champions of Serbia and Croatia — which was curbed in 1991 — could now be renewed in Europe’s top competition.
Red Star, which won the European Cup in 1991 as the old Yugoslav national league broke up, went through on away goals after a 1-1 draw with visiting Young Boys made the aggregate score 3-3.
Fans of Red Star parked a decommissioned Yugoslav army battle tank, used in the Balkan conflicts in the 1990s, outside their stadium for the game. Croatian media said the move was “a clear provocation.”
Dinamo advanced 3-1 on aggregate by drawing 1-1 at Rosenborg, leveling in the 71st minute from a rising, left-foot shot by Bosnia-Herzegovina midfielder Amer Gojak.
Dinamo will be in the pot of third-seeded teams and can be grouped with Red Star, which is in the lowest-ranked pot 4 at Thursday’s draw in Monaco.
For the second straight year, Red Star is the only team to play through eight games in four qualifying rounds to reach the lucrative group stage.
The Serbian team survived a tense end to the game after Young Boys leveled in the 82nd through an own goal by Red Star’s El Fardou Ben Nabouhane. Red Star’s Tomané was then sent off for getting a second yellow card during more than seven minutes of stoppage time.
The final places in the 32-team lineup will be decided in three more playoff games Wednesday, including Ajax hosting APOEL after a 0-0 draw in the first leg in Cyprus.