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. The 22-year-old Sock is playing his third tournament of the year after having surgery to repair a torn muscle in his pelvis in December. In other second-round matches, Russia's Teymuraz Gabashvili beat fourth-seeded John Isner of the United States 6-2, 7-6 (2), and fifth-seeded Santiago Giraldo of Colombia topped Janko Tipsarevic of Serbia 7-6 (2), 6-3.