Brazil forward Neymar has not featured for PSG since its 4-0 win over Angers on 6 October after picking up a hamstring injury on international duty.
The 27-year-old has started individual training and will step up his recovery next week, having been left out of Brazil's squad for their two friendlies this month.
PSG may also be without Icardi for their next league outing, though, after the on-loan Inter striker was substituted in the second half of Wednesday's 1-0 win against Club Brugge with a knock.
Head coach Thomas Tuchel said after the game that match-winner Icardi had been playing through the pain barrier, and he will undergo an assessment on a foot injury on Saturday (AEDT).
Thilo Kehrer is back in training ahead of the clash with Brest, but Ander Herrera will definitely miss out because of a thigh injury while Thomas Meunier is also out until after the international break.
Champions PSG lost 2-1 to Dijon last weekend but are seven points clear of second-placed Angers in Ligue 1.