Defending champions Lille claimed their first home win of the new Ligue 1 season after edging a thrilling contest against last season's runners-up Marseille.
Moussa Sow scored the only goal of the first period before Marseille surged ahead when Mathieu Valbuena struck twice in seven minutes.
OM's lead lasted just three minutes though as Aurelien Chedjou equalised before Sow scored his second from the penalty spot on 75 minutes to seal victory.
Lille's win moves them up to seventh but Marseille's early woes continued as they were left searching for their first win after four games.
OM had drawn their opening three matches and while a trip to the champions was untimely they began well as Benoit Cheyrou saw a long-range effort deflected wide with Mickael Landreau beaten.
Landreau was then at full stretch to keep out Andre Ayew's shot from 18 yards, before Lille went ahead against the run of play on 15 minutes.
Frank Beria found space down the left and fizzed in a cross that Sow reached just ahead of Steve Mandanda with an outstretched leg.
Lille maintained their advantage into the break but they were stung by a double strike from Valbuena soon after the resumption.
Loic Remy had already hit the post before Valbuena unleashed a spectacular strike on 57 minutes that took a slight deflection off Chedjou on the way in.
OM went ahead seven minutes later when, after Cheyrou saw his low free-kick expertly kept out by Landreau, Valbuena swooped on the rebound and drove in a shot the keeper could not keep out despite getting two hands to the ball.
Lille were level almost immediately, however, as summer signing Dimitri Payet picked out Chedjou who fired his shot between the legs of Mandanda.
Lille then regained the lead 15 minutes from the end when Rod Fanni needlessly felled Eden Hazard in the penalty area and Sow made no mistake to win the game.