Karel Mustmaa, an Estonian winger born in 2001, has joined Čukarički on a one-year loan from PAOK. Mustmaa, who can also play as a forward, spent the previous season with PAOK's second team, recording four goals and five assists in 24 matches. The Greek club had originally signed him from Benfica B in August 2025. Mustmaa had progressed through most of the Lisbon club's academy after arriving at their under-17 team from Estonian side Harju. He has made 5 appearances and scored 1 goal for the Estonian national team, and his contract with the Greek club runs until 2028. His current market value is estimated by Transfermarkt to be €250k.