The Argentine was substituted out of the Blaugrana's European tie at halftime after giving his side the lead, having suffered an apparent muscle strain.
The Argentine suffered the muscle strain towards the end of the first half, with the attacker hugging the touchline in the closing moments while talking with manager Tito Vilanova.
The Barca boss then chose to substitute the 25-year-old during the break, replacing the four-time Ballon d'Or winner with Cesc Fabregas.
Messi had already put the Blaugrana ahead in the 38th minute, latching onto a lofted Daniel Alves' pass, before striking the ball low past PSG goalkeeper Salvatore Sirigu. The game eventually ended 2-2.
"He will undergo further tests on Wednesday to determine the extent of the injury," Barcelona said on its Twitter feed.