Neymar went down after a robust challenge from Steeve Yago in the 56th minute, holding his left thigh as he left the field to be replaced by Kylian Mbappe.
Moise Kean scored the only goal early in the second half before Neymar limped off the pitch raising concerns about participating in the Camp Nou clash against his former club.
After the game, PSG manager Mauricio Pochettino said Neymar injured his adductor but wouldn't say how long he could be out.
"It's hard to know now, we'll see [Thursday] with the doctor, for the moment it's hard to say," Pochettino said. "Can he be there [at Barcelona] next week? I need more information. Is he affected in the adductors? Yes."
PSG will already be without the injured Angel Di Maria for the Barcelona game, who injured his thigh last Sunday against Marseille.