PSG coach Thomas Tuchel told a press conference on the eve of the game at the Parc des Princes that the pair are in good form and trained normally on Monday and Tuesday.
Tuchel said: “No problem, they will start tomorrow.”
Mbappe and Neymar sat out Saturday’s 1-0 win over Toulouse in the French league and were doubtful for the match against Liverpool after they picked injuries with their national teams during friendly games.
Neymar limped off with a right adductor problem while playing with Brazil against Cameroon and Mbappe sustained a shoulder injury against Uruguay.
PSG enters the crucial match at Parc des Princes with five points in Group C, one behind leaders Liverpool and Napoli. A victory would put the French club back in position to advance with another win in its final game.