Valbuena doubtful for Marseille's trip to Lille
"We will make a decision on Saturday," Baup was quoted by French media.
Valbuena picked up the injury in last weekend's 1-0 win against Girondins Bordeaux.
OM are second in the standings on 57 points with seven games left, seven points behind leaders Paris Saint-Germain.
Lille are fifth on 52 points.