SHENZHEN, China (AP) Sixth-seeded Jiri Vesely advanced to the quarterfinals of the Shenzhen Open by beating Zhizhen Zhang of China 6-2, 6-3 Wednesday.
The Czech player conceded only 10 points on his serve.
Vesely will next face top-seeded Tomas Berdych, who defeated Austin Krajicek of the United States 7-5, 6-3.
Simone Bolelli of Italy qualified for his seventh quarterfinal match of the season after eighth-seeded Victor Estrella Burgos retired with a back injury while trailing 6-4, 4-0.
Tommy Robredo will face Bolelli in the quarterfinals after eliminating Hiroki Moriya of Japan 7-5, 6-3.