NEW YORK (AP) Sam Querrey defeated fellow American Bradley Klahn 6-3, 4-6, 7-5, 6-4 in the first round of the U.S. Open on Wednesday.

The 20th-seeded Querrey had 19 aces but 11 double-faults. He has won four titles this year - only Rafael Nadal has more. Querrey broke Klahn's serve to clinch the victory.

The 20-year-old Klahn got in on a wild card to make his Grand Slam debut. He won the NCAA singles title for Stanford this year. Klahn had 54 unforced errors.