Marseille conceded a last-minute equaliser at St. Etienne as their Ligue 1 title hopes were hit by a third straight draw.
Mevlut Erdinc's injury-time goal earned the hosts a 2-2 draw and denied Marseille the chance to move level on points with second-placed Paris St Germain, keeping them four points behind leaders Lyon.
A quick-fire second-half brace from substitute Michy Batshuayi, who scored one minute and four minutes after coming on, had turned the game in the visitors' favour following Max Gradel's penalty.
Les Verts started well and within the first 10 minutes had two attempts at Steve Mandanda's goal.
Ricky van Wolfswinkel went agonisingly close with a header from Gradel's cross before the Ivory Coast international opted to shoot from 20 yards but failed to find the target.
The hosts continued to create the better openings early on, with Van Wolfswinkel inches away from getting a telling touch to Fabien Lemoine's flick-on.
An opportunity fell OM's way with just over half-an-hour played, but Dimitri Payet's chip in behind found Andre-Pierre Gignac flat-footed and Stephane Ruffier was allowed to claim.
As halftime approached Gianelli Imbula forced Ruffier to save a swerving effort with his legs before Mandanda scurried across his goal to claim Gradel's free-kick.
Gradel put the hosts in front nine minutes after the break.
Defender Jeremy Morel clumsily hauled down Romain Hamouma inside the area and, from the resulting spot-kick, Gradel sent Mandanda the wrong way.
But the introduction of Batshuayi in the 63rd minute proved an inspired one for Marseille.
A minute after coming on he wriggled free of the hosts' defence and fired past Ruffier.
And, three minutes later, he was on hand to tap Romain Alessandrini's cross home at the near post.
But the hosts grabbed a leveller with just a few minutes left to play in injury-time.
Yohan Mollo's teasing delivery from out wide caused havoc in the OM area and Erdinc was on hand to head home from close range.