The 17-year-old Turkish goalkeeper Deniz Dönmezer attracted the interest of clubs including Beşiktaş. He joined Kayserispor in September 2025 and has a contract with the club until June 2028. The Türkiye U19 international has 2 caps and has made 4 appearances in the 1.Lig this season. His market value is currently estimated by Transfermarkt to be €1.00m.