London Calling! The #NittoATPFinals Group Guga Kuerten: 🇷🇸 @djokernole, 🇩🇪 @alexzverev123, 🇭🇷 @marincilic, 🇺🇸 @johnrisner. Who will emerge? _ 📸: 2018 #USOpen. #tennis #instasport #atpworldtour #novakdjokovic #alexanderzverev #marincilic #johnisner