Marseille is 11 points behind Lille after its remarkable comeback.
Lyon had won only one of its past four league matches but took the lead in the 17th minute when Alexandre Lacazette was given too much space to collect Yoann Gourcuff's pass and wrongfoot Marseille goalkeeper Steve Mandanda.
Bafetimbi Gomis doubled Lyon's lead two minutes from halftime after being unselfishly set up by Henri Bedimo but Andre-Pierre Gignac reduced the deficit in first-half stoppage time with a powerful strike from 30 meters.
Marseille leveled in somewhat fortunate circumstances in the 79th minute when Florian Thauvin's free kick was deflected over goalkeeper Remi Vercoutre by both Bedimo and Lacazette in the Lyon wall.
''Gignac's goal completely changed the match,'' Marseille interim coach Jose Anigo said. ''There was a positive reaction in the dressing room. That shows the state of mind that we're getting into. In any case, it's an important point. We couldn't win this match, so it meant we mustn't lose.''