American Ryan Sweeting launched his title defence at the US Men's Clay Court Championship on Tuesday with a 6-3, 7-6 (8/6) victory over Brazilian qualifier Ricardo Mello.
Sweeting, trailing 5-6 in the second set, saved two set points against his serve as he held on to force the tie-breaker, sealing the victory on his fourth match point.
In other matches at the Houston tournament, Tatsuma Ito won an all-Japanese clash with Go Soeda 6-4, 7-5, the first tour-level meeting between the two compatriots.
Ito booked a second-round clash with fourth-seeded Argentinian Juan Monaco.
Italy's Paolo Lorenzi set up a meeting with third-seeded Feliciano Lopez of Spain with a 6-7 (3/7), 6-2, 6-3 victory over Wayne Odesnik.
Qualifier Horacio Zeballos booked a marquee second-round clash with America's Davis Cup hero John Isner via a 6-3, 6-3 victory over Romanian Adrian Unger.
Isner, seeded second in Houston, delivered two singles victories, including the clinching four-set win over Jo-Wilfried Tsonga, in America's Davis Cup quarter-final victory over France in Monte Carlo at the weekend.
Isner had beaten Swiss great Roger Federer on clay in the United States' 5-0 first-round Davis Cup whitewash of Switzerland in February.
He has also beaten world number one Novak Djokovic this year, in the semi-finals of the hard-court Indian Wells Masters.
"I'm a much more confident player," said Isner, who flew in late to Houston and is to open his campaign on Thursday after enjoying a first-round bye.
"To be able to compete in this game you have to be confident, and that's what I have on my side right now."
Mardy Fish, ranked ninth in the world, one spot in front of Isner, is the top seed at the $442,500 event.
In the second round, Fish will face American Michael Russell, a Houston resident who rallied from a set and a break down for a 2-6, 7-5, 6-1 win over Spain's Daniel Gimeno-Traver.