Defending champion Olympiakos could not hold on to an early lead at Xanthi and was held to 1-1 in the Greek league on Saturday.
Defender Bjorn Engels, in his debut for Olympiakos, opened the scoring when he headed the ball in following a Seba corner kick.
During a Xanthi counterattack, Christos Lisgaras beat Olympiakos goalkeeper Stefanos Kapino to a long ball and headed in the equalizer before halftime.
Olympiakos still leads the standings, but second-place Panionios has a chance to go on top when it meets visiting Panetolikos on Sunday.
Also, Atromitos vs. Giannena ended in a scoreless draw, and newcomer Lamia beat host Asteras 3-1 for its first ever win at the top division. [AP]