The Paris Saint-Germain forward suffered the problem following a cross and had to be substituted.
It means Neymar is now a major doubt to face Liverpool in the Champions League next Wednesday.
PSG team-mate Maxim Choupo-Moting has admitted being without the forward would be a blow.
He said: “It would be worrying because he is a very important player, as all the players (at PSG) are.
“No player is more important than the team.
“He’s a great player though and I hope he is not injured for a long time.”
Choupo-Moting had a similar injury at the end of his time with Stoke and hopes Neymar’s issue is not as problematic.
“I talked quickly to him but it was just after the injury,” he added.
“I think it’s not too too serious. I hope he will be ready next week for us.
“He wanted to play. He really had an injury and felt something. I had it at Stoke.
“It was my last game for Stoke, I was injured for two months. I hope for him it is not that serious.”
Kylian Mbappe could also miss the clash with Liverpool after he was injured on international duty with France.
The striker was in visible pain holding his shoulder as he left the field.
But France boss Didier Deschamps was unable to confirm the extent of the problem following the match.
”He has a sore shoulder, he’s fallen badly,” he said.
“He will have to see with the medical staff. I hope it’s not bad.”