PAOK dropped its first points at home this season, conceding a 1-1 draw to crosstown rival Aris on Sunday.
The first Aris goal by Fran Velez, whom television replays showed to have come from an offside position, denied PAOK another home win as it canceled out Adelino Vieirinha’s opener late in the first half.
However PAOK remains unbeaten and its last major test is coming next week when it visits Panathinaikos. PAOK still needs 17 points from its eight remaining games to be crowned champion.
Main challenger Olympiakos will have the chance to reduce the gap from the top to seven points when it hosts OFI Crete in Piraeus on Monday.
Third-placed AEK struggled to beast bottom team Apollon Smyrnis 2-1. Facing the mighty wind at the Olympic Stadium of Athens on Saturday, AEK got two goals from Lucas Boye and Apollon one from Hilal El-Helwe.
AEK has opened a three-point gap from fourth Atromitos that drew 1-1 at Asteras Tripolis on Saturday. Aris is fifth and Panathinaikos sixth, three points behind Aris, after losing 2-0 at Panionios on Sunday.
Lamia has joined Panetolikos and Xanthi in seventh, after coming from behind to down visiting Larissa 2-1. Panetolikos hosts PAS Giannina on Monday, while Xanthi lost 1-0 at home to Levadiakos, in a game that started on Saturday, stopped after 22 minutes due to gale-force winds and resumed on Sunday.