Neymar left the field with an apparent groin injury in Brazil’s 1-0 friendly win over Cameroon in Milton Keynes on Tuesday.
The Paris Saint-Germain attacker pulled up on five minutes when attempting a shot from outside the box and was replaced by Everton’s Richarlison – who got the only goal of the game.
The world’s most expensive player scored during his country’s previous friendly in a 1-0 victory over Uruguay at Arsenal’s Emirates Stadium last Friday.
His injury couldn’t be more badly times as PSG host Toulouse in Ligue 1 before welcoming Liverpool to the French capital in a pivotal Champions League tie on November 28.
The Parisians are third in the group – behind Liverpool and Napoli – and must beat Jurgen Klopp’s men to avoid a humiliating first round exit.