ATP Tour To Return To Belgrade The ATP Tour returned to Belgrade in 2021 for the first time in nine years with the Serbia Open, an ATP 250 clay-court event, at the Novak Tennis Center. The world-class facility, where World No. 1 Novak Djokovic regularly trains, boasts 14 tennis courts, including 11 clay and three hard courts. The tournament had relocated from Budapest, Hungary in 2021.