Olympiacos inflicted a third straight defeat on Panseriakos at the start of the Greek Super League season thanks to Marko Pantelic's first-half goal.
The newly-promoted side continued to struggle, with Pantelic's goal in the 32nd minute giving visitors Olympiacos their second victory of the season.
AEK Athens came from two goals down to draw with Asteras Tripoli. Salim Arrache put Asteras ahead after 44 minutes and substitute Constantinos Fortounis doubled their lead with nine minutes remaining.
However Rafik Djebbour pulled a goal back two minutes later and Ignacio Scocco grabbed an equaliser for the home side in the 87th minute, forcing a 2-2 draw.
Kerkyra climbed to third in the table after a 3-1 win over Atromitos, with Denis Epstein netting twice and Thanassis Tsigas on target before Emanuel Perrone scored a consolation.
Bosko Balaban was the matchwinner for Panionios as they defeated Aris Salonika 1-0.
Aris had Mehdi Nafti sent off after 50 minutes, and former Aston Villa and Dinamo Zagreb striker Balaban pinched the three points for Panionios by netting with four minutes remaining.
PAOK Salonika remain unbeaten, with one win and two draws, after being held 1-1 by Olympiacos Volou.
Juan Martin put Olympiacos Volou one up after 22 minutes but Vladimir Ivic hauled PAOK level in the 38th minute.