Returning finalist John Isner edged out Ryan Harrison 7-6 6-4 in the first round of the ATP Tour's US Clay Court Championships.
Isner finished runner-up to Argentine Juan Monaco last year in Houston and he started another pursuit of the title after taking the crucial points in an evenly contested match.
Seventh-seeded Paolo Lorenzi also reached the next stage after a comfortable 6-2 6-2 win over Austrian qualifier Gerald Melzer.
The 31-year-old Italian Lorenzi fired down three aces, had two double faults, and won 68 per cent of his first-serve points.
Robby Ginepri finally ended his miserable run of results with a 6-2 6-2 win over eighth-seed Michael Russell.
Ginepri picked up his first tour-level win in more than a year in convincing fashion, while in another all-American first round match, wild card Jack Sock converted two break points chances to beat qualifier Bradley Klahn 7-6, 6-3.