It seemed as if the hosts had to settle for a draw, but two goals in the final 10 minutes of the game helped them to a vital home victory and eliminated Montpellier.
Portuguese midfielder Paulo Machado gifted the hosts the lead early on when he found the net from inside the area, but Younes Belhanda restored parity halfway through the second half from the penalty spot. Leandro Greco and Kostas Mitroglou then added their names to the score sheet in the closing stages of the game to help the hosts to victory.
The Greek giants started the match the better side of the two and needed only four minutes to open the scoring. Greco danced past his direct opponent down the left before sending in a low cross for Mitroglou, who saw his shot hit the upright. Machado was alert, though, and tapped home from close range to make it 1-0.
Mitroglou then came close to doubling his side's lead after some sloppy defending from Mapou Yanga-Mbiwa; however, Montpellier goalkeeper Geoffrey Jourdren pulled off a superb save to bail out Yanga-Mbiwa and deny the prolific attacker.
Montpellier then took over the initiative and created a number of dangerous chances within the space of minutes. Roy Carroll first denied Jonathan Tinhan with a good reflex, before the experienced glovesman did well to collect Joris Marveaux's header from close range.
There was little Carroll could do to stop Belhanda's attempt in the 67th minute, though. The referee had no other choice but to award the away side a spot kick after Dimitris Siovas pulled down Camara inside the area, and the playmaker had no trouble slotting home from the spot.
Olympiakos kept on pushing and were eventually rewarded in the 80th minute. The Montpellier defense allowed Greco too much space after a corner kick, and the winger fired home from inside the area to make it 2-1. Things would only get worse for the French champions from here on, and Mitroglou doubled the deficit only minutes later. A fine cross from Jose Holebas reached the prolific attacker, who volleyed past the helpless Jourdren after escaping Yanga-Mbiwa's attention.