Kylian Mbappe vented his frustration towards manager Thomas Tuchel after being substituted, but the Paris Saint-Germain star could be punished for his actions.
Mbappe was taken off with just over 20 minutes remaining in the second half and was not happy with the decision.
The Frenchman appeared to argue with Tuchel when coming off, although it's not the first time Mbappe has reacted to being taken off in a game.
"I'm the coach, someone has to decide who goes out and who comes in. It's me," Tuchel said after the game, as per the Sun.
"[Mbappe] is very intelligent, he knows what he is doing. He doesn't like going out, nobody likes going out. These are not good images, but we are not the only club that has to deal with this sort of thing.
"It's not good, because it opens up subjects that go against the team's state of mind. Too bad. I am not angry, but I am sad because it is not necessary.
"I explained to him why we did this, and it will stay that way. I will always decide the technical aspects. We don't play tennis, we play soccer and we have to respect everyone."
When asked about a possible punishment, Tuchel added: "I don't know, I have to think, I have to sleep. I will make a decision tomorrow," he added.
"We have training at 11am, we will talk about the match with the group. I'll see if I talk about this or if I do it individually. It will depend on my night's sleep too."