Panathinaikos edge closer to summit
Jesualdo Ferreira's Greens went ahead in the first minute through top scorer Djibril Cisse, who beat Xanthi goalkeeper Sotiris Liberopoulos with a neat chip.
Cisse, linked in the media with a return to former club Liverpool, has now scored 14 league goals this season.
Substitute Lazaros Christodolopoulos added a second goal for the visitors in the third minute of added time when he latched on to a Kostas Katsouranis flick-on and rounded Liberopoulos before applying a simple finish.
The result moves champions Panathinaikos on to 34 points from 16 matches as the league returned to action following the winter break. Their arch-rivals Olympiakos, who have 36 points from 15 games, host Iraklis on Wednesday.
Aris moved up to fifth place with a 1-0 win over Kavala, with Carlos Ruiz scoring the only goal in the third minute, while Atromitos piled more pressure on basement club Larissa by beating the Thessaly club 3-0.
Larissa remain rooted to the foot of the standings with just 11 points from 16 matches.