Top-seeded Andy Murray continued his dominating form at the China Open with a 6-2, 6-1 victory over Andrey Kuznetsov on Wednesday, while upstart Alexander Zverev ousted American Jack Sock 6-4, 6-2 in second-round action.
Murray will next face countryman Kyle Edmund, the British qualifier who upset No. 7 seed Roberto Bautista Agut 6-4, 4-6, 6-4 on Wednesday. Murray won the only previous FedEx ATP meeting between the two.
"(On) the day of the match, it's always a little bit uncomfortable, because normally when you see your friends and stuff in the locker room, you have a chat, joke around a bit," Murray said. "But on match days, it always tends to be a little bit more serious.
"Once you get out on the court and start competing, it's fine. After the match, again, it's always fine. But it's just sort of the couple hours before when you see each other in the locker room, it can be a little bit uncomfortable."
Steve Johnson continued a rough day for the American men, falling 7-5, 6-7 (9), 6-4 to unseeded Grigor Dimitrov in first-round play. Pablo Carreno Busta, Guido Pella and qualifier Adrian Mannarino also won their first-round matches.
--Top seed and home favorite Kei Nishikori was forced to withdraw from his second-round match at the Japan Open after suffering an acute injury to his gluteus muscle while leading Joao Sousa 4-3 in the first set. Sousa advanced to the quarterfinals, where he will play No. 5 seed David Goffin, a 6-3, 7-5 winner over Jiri Vesely on Wednesday.
No. 4 seed Marin Cilic also advanced with a three-set victory over Fernando Verdasco 4-6, 7-5, 7-5. Gilles Muller upset No. 3 seed Tomas Berdych, who was coming off defending his Shenzhen Open title last week. Juan Monaco also moved into the quarterfinals with a 7-6 (3), 6-3 victory over James Duckworth.
Nishikori said he felt the injury when he stepped awkwardly during a long rally, and wasn't immediately certain of his status for the ATP World Tour Finals in Singapore next week.
"It was hugely disappointing to have to retire from my match, especially since I was playing much better than during my first round," Nishikori said. "The pain came suddenly, which was very alarming to me because I have never felt something like this before.
"It is possible that the injury was due to an accumulation of fatigue and stress, but I came into this tournament with a lot of rest and feeling very ready. It also didn't feel related to the other injuries I've had this year. I will get examined and hope to recover in time for my next tournament."