Osimhen was replaced by Nico Gaitan 10 minutes from time after sustaining an injury in Friday’s 2-0 away win against Angers.
But Galtier does not think the issue is a serious one and Osimhen should be back available soon.
“It was nothing serious. He had to go out because of a muscle injury. We don’t know the extent yet and the length of his unavailability,”Galtier said after the game.
“We will know that tomorrow (today) with the tests.”
Osimhen opened scoring for Lille in the 14th minute after he was set up by Jonathan Bamba, while Renato Sanches added the second 15 minutes from time.
He has scored 12 goals and bagged four assists in 23 league appearances for Lille this season.