Defending champion Fernando Verdasco has defeated 18-year-old Hyeon Chung 7-6 6-2 in the second round of the ATP claycourt tournament in Houston.
The sixth-seeded Verdasco, from Spain, survived stiff early resistance from Chung, then broke the South Korean player in the fifth game of the second set and coasted to the victory.
Chung was the first South Korean player to win a main-draw match in the tournament since Hyung-Taik Lee reached the final in 2001.
American Jack Sock upset second-seeded Roberto Bautista Agut of Spain 6-4 6-4.