Olympiacos closed the gap at the top by beating Kerkyra 4-0, with Marko Pantelic scoring all of the goals, while there were also victories for Panathinaikos, Asteras Tripoli, Ergotelis and Panetolikos.
A free-kick goal from Konstantin Vassilijev just five minutes from time secured a 1-1 draw for Estonia with Serbia in a UEFA EURO 2012 qualifying Group C match.
Northern Ireland's UEFA EURO 2012 qualification hopes took a heavy blow in Belgrade as they conceded twice in the second half to surrender a hard-earned lead against Group C rivals Serbia.
Olympiacos eased to victory over Ergotelis in 4-0 result, putting them 13 points clear at the top of the Super League, and second place Panathinaikos were defeated by Larissa.
FIFA.com looks at how the arrival of coach Ernesto Valverde and four influential foreign players is helping to push Piraeus giants Olympiacos back to the summit of Greek football,
Olympiacos beat nine-man Asteras Tripoli 3-0 to move to the top of the Super League, ahead of Panathinaikos, who beat Panionios 2-1.