In-form Ghana striker Asamoah Gyan suffered another setback in his return to full fitness after failing to complete Tuesday's training session.
Gyan, reported to have aggravated an old injury, returned to the hospital and remains a doubt for this weekend match against Paris Saint Germain.
The 23-year-old was hamstrung a fortnight ago and sat out last Saturday's French Ligue 1 match but returned to training this week.
His 13 goals this term makes him the third joint top scorer in the French top-flight.