The Brazil forward was substituted late on against Saint-Etienne following a challenge which led to damage to his ankle.
The club confirmed the news and released a statement detailing the full extent of the injury.
"The examinations carried out last night confirm that Neymar Jr suffered from a sprained left ankle with ligament damage," PSG said.
"An unavailability of 6 to 8 weeks is expected. A new update will be made in 72 hours to clarify the diagnosis."
Following the match, manager Mauricio Pochettino had hoped that the injury wasn't too serious.
"We hope that it is nothing too serious and that he can come back to help the team as soon as possible," he said.
The Argentinian did admit the club were worried and unfortunately for the PSG boss, he will now be without one of his star men for the foreseeable future.
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