HOUSTON, April 10 (UPI) -- Fifth-seeded John Isner needed a first-set tiebreaker but advanced with a victory Tuesday in first-round play at the U.S. Men's Clay Court Championship.
Isner, who finished second in last year's event at Houston, moved on with a 7-6 (7-4), 6-4 defeat of fellow American Ryan Harrison at River Oaks Country Club.
He now goes on to face wild card Jack Sock of the United States, who posted a win over fellow American Bradley Klahn 7-6 (7-3), 6-3.
Joining him in the second round was Spain's Fernando Verdasco, who also had to get past a first-set tiebreaker before prevailing over American wild card Steve Johnson 7-6 (7-5), 6-2.
Elsewhere Tuesday, seventh-seeded Paolo Lorenzi of Italy downed Austrian qualifier Gerald Melzer 6-2, 6-2 and Robby Ginepri dispatched No. 8 fellow American Michael Russell 6-2, 6-2.
Italian Flavio Cipolla and Lithuanian Ricardas Berankis also recorded wins on Day 2 in Houston.