Defending champion John Isner and top seeded Jo-Wilfried Tsonga of France both won Tuesday in the second round of the Winston-Salem Open.
The third-seeded Isner was pushed to three sets before beating Slovakia's Martin Klizan 4-6, 6-3, 7-5.
Tsonga, the highest-ranked player (sixth) in the final hard-court tournament before the U.S. Open, beat Brazil's Thomaz Bellucci 6-3, 7-6 (7-2).
Also advancing to Wednesday's round of 16 were second-seeded Tomas Berdych of the Czech Republic, fourth-seeded Alexandr Dolgopolov of the Ukraine, sixth seed Marcel Granollers of Spain, seventh-seeded Sam Querrey, ninth-seeded Feliciano Lopez of Spain, No. 13 seed Jurgen Melzer of Austria, No. 14 seed David Nalbandian of Argentina and 16th seed Jarkko Nieminen of Finland.
