The Brazil international was forced off against the Corsicans after 57 minutes, and is not likely to return to match action until the Feb. 8 clash with Bastia.
"The MRI that was performed today confirms a femoral biceps injury. He will be unavailable for an estimated three weeks at the minimum," a statement on the PSG's official website confirmed.
Friday's 0-0 draw with Ajaccio saw Les Parisiens concede the top spot in Ligue 1 to Olympique Lyonnais, which trails by two points but has a league-best plus-24 goal differential.
Follow GOAL.COM on Twitter
- Sports & Recreation