The Croatia youth international has played just eight top-flight games for Istra but is set to move to Stamford Bridge for a fee beginning at €1 million (£800,000)
Chelsea are close to securing a deal for Croatia youth international goalkeeper Ivan Brkic, Goal understands.
The 19-year-old has only made eight top-flight appearances for Istra but has already attracted attention from multiple English clubs.
The Blues are firmly ahead in the race to sign him, however, and sources have told Goal that his switch to Stamford Bridge is close to completion, with the Croatian club asking for €1 million (£800,000) plus bonuses.
Brkic would become the fourth Croatian player on Chelsea’s books, along with Mario Pasalic, Stipe Perica and fellow keeper Matej Delac.
Jose Mourinho has already made four signings this summer, having recruited Diego Costa, Cesc Fabregas, Filipe Luis and returning club legend Didier Drogba.