PSG said in a medical bulletin on Monday that Neymar "had some pain in his groin since returning from international duty and will undergo more treatment over the next few days before returning to full training."
The world's most expensive player scored for Brazil in their 4-1 World Cup qualifying win against Uruguay last Thursday, playing 90 minutes in that game having also featured in their 0-0 draw in Colombia the previous weekend.
He didn't play for PSG as they beat Angers 2-1 in Ligue 1 last Friday, a game also missed by Lionel Messi.
The Argentine should return against Leipzig at the Parc des Princes as PSG look to build on their 2-0 win over Manchester City in their previous Champions League outing last month.
Neymar, meanwhile, will hope to recover in time to play Marseille next weekend.
"The priority is always the health of the players. 'Ney' has a small issue which we hope will only keep him out for a few days," PSG coach Mauricio Pochettino told reporters on Monday.