United States international Timothy Weah tore his hamstring again in action for Lille on Sunday as he made his return from a six-month lay-off.
Former Paris-Saint Germain striker Weah suffered the same injury in August, just weeks after signing a five-year deal at Lille.
The 19-year-old - son of former Ballon d'Or winner George Weah - made only his third appearance for Lille as an 80th-minute substitute against Marseille in Ligue 1.
Although Weah played out the remainder of the 2-1 defeat, he confirmed on Instagram on Monday he had suffered a setback.
Lille then clarified the injury on Twitter as a right hamstring tear, with no time frame given for his return to the field.
"Our forward will now begin a process of rehabilitation," the post read. "The entire team at LOSC wish Tim a speedy recovery."
Weah wrote on Instagram: "Felt amazing to be on the field again with my team-mates after six months, and thank you to our beautiful supporters who came out and cheered us on.
"But unfortunately for me, things didn't go as planned and I've injured myself again.
"Better days will come and I know that God is watching over me. Small setback for a major comeback."