The Paris Saint-Germain striker missed two penalties in the first ten minutes of the game against Montpellier and had to be substituted shortly afterwards due to injury.
The situation could be a problem for PSG in the Champions League round of 16 duel against Bayern Munich, with the first game scheduled for 13 days from now.
In the 20th minute of the first half, Mbappé received a knock on the thigh when he was fouled and had to leave the pitch, giving way to young Hugo Ekitike.
Television cameras showed the French striker placing his hand on his left thigh, in a typical muscle injury gesture, as he left for the dressing rooms.