ATP roundup: Nick Kyrgios loses in return from surgery

Yibing Wu put his best foot forward in the Boss Open on Tuesday with a 7-5, 6-3 first-round victory over Nick Kyrgios, who was playing in his first match since undergoing knee surgery in January.

Wu, of China, withstood 15 aces from Kyrgios, who was struggling physically and told his team he was unable to "walk without pain." Wu advanced to the second round of the tournament in Stuttgart, Germany.

Also, Aslan Karatsev o