On September 9, Auxerre officially announced that Chile international centre-back Francisco Sierralta has joined Polish club Piast Gliwice on loan for one season, with an option to buy included in the contract.

Sierralta joined Auxerre from Watford in the summer of 2025 and made his first appearances for the club in Ligue 1 last season. He made 10 appearances in total and scored one goal.
Sierralta will now head to Poland to begin a new stage of his career, competing in the Polish top flight with Piast Gliwice. The one-year loan deal, which also includes a purchase clause, will provide him with a new challenge and more opportunities to play.
Auxerre sent their best wishes to Sierralta: "Wishing you a wonderful season in Poland, Francisco!"