Vassilis Torossidis and Kostas Mitroglou complete a second-half turnaround to give Olympiakos their first points in this season's Champions League.
Olympiacos produced a late winner to deny Montpellier their first ever Champions League victory this evening.
The French champions took the lead on 49 minutes through Gaetan Charbonnier, who exchanged passes with John Utaka before unleashing an unstoppable drive from the edge of the penalty area.
Montpellier continued to dominate possession going into the closing stages but were pegged back by an incisive counter-attack.
Vassilis Torossidis latched onto a speculative long ball before using his strength to hold off Souleymane Camara to tuck home from close range.
In the second minute of stoppage time Kostas Mitroglou completed the turnaround after a fine assist from Djamel Abdoun to give the Greek side all three points.
Olympiakos now sit in third place in Group B behind Arsenal and Schalke, leaving Montpellier languishing at the foot of the table with just a single point.
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