Defending champion Olympiakos scored a goal in each half at Panionios to win 2-0 and go top of the Greek league on Saturday.
Alberto Botia scored with a 15th-minute header off a corner, and Luka Milivojevic added the second with a free kick in the 64th.
Both teams had a player sent off with a second yellow card late in the game — Panayiotis Retsos for Olympiakos, and Valentinos Vlahos for Panionios.
Olympiakos is two points ahead of Panathinaikos — which can reclaim first place if it beats visiting Xanthi on Sunday — and three ahead of Panionios.
Also Saturday, Asteras picked up its first points of the season after four losses, beating Platanias 2-0.
Panetolikos thrashed Kerkyra 4-0.