Papa Bouba Diop scored two second-half goals to help AEK Athens beat rival PAOK 3-0 on Sunday and grab the lead midway through the Greek playoffs race.
Traianos Dellas had opened the scoring for AEK.
In the other playoff game, Volos came from behind to beat visiting Panathinaikos 2-1. Second-half goals from veteran Ilias Solakis, playing for his 13th professional club in 17 seasons, and Juan Martin canceled out Sebastian Leto's first-half effort.
After three rounds, AEK leads the playoffs race with seven points, one ahead of PAOK. Panathinaikos is on four points and Volos trails on three.
The winner of the six-round, home-and-away series joins Olympiakos in next season's Champions League. Two Europa League spots are also up for grabs.
AEK nearly scored in the opening seconds,when a freekick by Nacho Scocco hit the post.
The hosts, playing in an empty Athens Olympic Stadium as punishment for fan violence in the Greek Cup final last month, finally opened the scoring in the 21st when Dellas latched on to a failed clearance by PAOK's Bruno Cirillo to head home from close range.
Diop, the veteran Senegal national, made it 2-0 in the 47th when he headed the ball home off a Scocco freekick.
PAOK had two good chances to pull a goal back in the 55th and 64th minutes but Sebastian Saja blocked shots by Giorgos Fotakis and Zlatan Muslimovic.
It was AEK which scored instead in the 68th. Dellas met a deep ball by Roger Guerreiro and headed the ball on, two defenders failed to clear and Diop scored with a close-range shot.
At Volos, the hosts had an early scare when goalkeeper Eldin Jakupovic blocked a shot by Loukas Vyntra with some difficulty in the 2nd minute. But Volos dominated the next 30 minutes, missing five good scoring chances while hitting the woodwork twice, through Martin and Mario Breska.
Five minutes after sending a thundering freekick into the crossbar, Breska handed Panathinaikos its goal on a plate in the 33rd when he tried to dribble past Sebastian Leto in his own area. The Argentinean striker stole the ball and scored from a tight angle.
The hosts, who beat Panathinaikos twice in the regular league season, also dominated the second half and equalized in the 51st, when Solakis headed the ball into the underside of the crossbar and past the goal line off a Zoltan Szelesi cross.
Martin scored the winner in the 63rd with a header from a freekick by Breska.
Panathinaikos' efforts to equalize came to nothing.
On Wednesday, Panathinaikos hosts Volos and AEK travels to Thessaloniki to play PAOK.
