Marseille have confirmed forward Bakari Kone fractured his cheekbone during the 1-0 defeat to Lyon in the last 32 of the Coupe de France.
The Ivory Coast international was knocked out when his head collided with the knee of Lyon goalkeeper Hugo Lloris midway through the first half of the match at the Stade Gerland.
Kone spent the night in hospital where he underwent tests, and is now due to see a face specialist.
"After his violent clash with Lyon goalkeeper Hugo Lloris, Bakari Kone was transported to a Lyon hospital where he underwent a scan," read an OM statement.
"This revealed a fracture of the arch of his cheek."
OM will wait to see the specialist's verdict before estimating how long Kone will be out of action for.