The Chelsea playmaker feels that the Ligue 1 side has a fighting chance against the Catalans but a lot will hinge on the Argentine's availability.
The two sides played out a 2-2 draw at Parc des Princes last week with the Argentine forward limping off before halftime with a muscle injury.
The four-time Ballon d’Or winner was forced to sit out the 5-0 win over Mallorca on Saturday and the Belgian feels his availability could decide the tie.
“It will depend on Messi, if he plays or not, to me, Paris can exploit [his absence],” he told Le10Sport.
“It will be complicated [for PSG], because we know Barca never give up at [Camp Nou]. But PSG have experienced players. It will be good for French football for a team to reach the semifinal of the Champions League.”
Both sides currently lead their domestic leagues with the Liga outfit ahead of arch-rival Real Madrid by 13 points, while Carlo Ancelotti’s side is seven points above Olympique de Marseille.