Heinze header helps Marseille sink PSG
Marseille were clearly the better side in front of their home fans and took the points courtesy of a 25th minute headed goal by Argentina defender Heinze, a former PSG player.
With 22 points from 12 games, the former European champions have closed the gap on champions Girondins Bordeaux, who lost to Valenciennes on Saturday, to three points.
The Paris club have dropped one place to 13th in the 20-strong league, nine points off the pace.
Friday's game was postponed from October 25, when it had to be cancelled because several PSG players were diagnosed with the H1N1 virus.
The match was called off at the last minute after PSG fans had already arrived in Marseille, where some clashed with OM supporters.
Twenty people, including 11 police officers, were hurt.
Some 650 police were on duty in an around the stadium on Friday, with about 1,000 PSG fans having travelled to Marseille. No major incidents were reported.
PSG have struggled for years to keep their most violent supporters under control and their matches against Marseille have often been marred by crowd trouble.