Marseille will await updates on Andre-Pierre Gignac's condition after the striker was forced out of Wednesday morning's training session with an injury.
The France international damaged his left ankle when he was caught by a heavy tackle from team-mate Pape M'bow, with L'Equipe reporting that Gignac reacted angrily before heading back to the dressing room.
OM confirmed on their website: "During this morning's practice match Andre-Pierre Gignac, following a collision with Pape M'bow, had to leave his colleagues. The striker returned to the clubhouse for treatment."
Defender Souleymane Diawara, rebuilding his fitness following a knee ligament injury, came through the full session unscathed.