Kylian Mbappe's injury is not serious and Monaco coach Leonardo Jardim expects him to be available again in two to three days.
Mbappe limped off with 15 minutes to go as Monaco started the defence of their Ligue 1 title with a 3-2 win over Toulouse on Friday.
But Jardim quickly allayed fears over the teenager, who is arguably the hottest property in world football having been linked with Real Madrid, Barcelona and Arsenal.
Speaking at a post-match media conference, Jardim said: "It's nothing serious. In two or three days it will be better."
Monaco visit Dijon in their next Ligue 1 game in eight days' time.