The Serb has now locked in four Top 20 players for his four-city Balkan Tour.
The World No.27 is currently out on bail and awaiting a preliminary court date for "violence against a family member committed in the presence of a minor."
The tournament is still scheduled to start on September 20, despite rumors that it is considering moving back a week to accomodate the US Open.
It wasn't supposed to be like this - but it's still a pretty amazing roof!
The two sporting legends joined Vasek Pospisil to share their love for tennis on Tennis United.
The World No.1 has signed players such as Grigor Dimitrov and Dominic Thiem to join the four-city series, which will be played behind close doors.
Family and famed rivals inspired former No. 1.
