Arsenal-owned AS Saint-Etienne defender William Saliba will miss Les Vert's clash with Stade Brestois 29 due to a niggling groin injury, with an October return mooted.
The 18-year-old burst onto the scene last season, making 16 appearances - eight of them clean sheets - to help his side to a fourth-place finish.
English Premier League side Arsenal were duly impressed, signing the France U20 international to a five-year deal in July before loaning him straight back for the 2019-20 Ligue 1 Conforama campaign.
Saliba missed the opening day 2-1 win at Dijon FCO, though, and has now undergone surgery on the injury. An expected six-week absence means he could return for the Derby du Rhône clash with Olympique Lyonnais in October, should all go to plan.
"Saliba had an operation earlier this week," explained Sainté coach Ghislain Printant. "We'll take our time with his return."