Marseille scored a late equaliser to share the spoils with Strasbourg on Friday, but the 1-1 draw at home was a missed opportunity in the race for a Europa League spot.
Striker Dario Benedetto came off the bench to head home Luis Henrique's cross from the left in the 86th minute, as sixth-placed Marseille moved level on points with Lens in fifth for a Europa League spot.
Lens remained ahead on goal difference but that could change after they visit second-placed Paris Saint-Germain on Saturday.
Marseille went close in the 17th when Florian Thauvin's corner was met by defender Leonardo Balerdi, but his close-range shot was saved by goalkeeper Matz Sels.
Marseille goalie Steve Mandanda made two saves from midfielder Dimitri Lienard in the second half, but he was powerless to stop central defender Stefan Mitrovic from heading in Lienard's 74th-minute corner.