”I play pretty well in the tight moments,” said John Isner. (Jonathan Newton/The Washington Post)

Just months removed from his college days at Georgia, John Isner announced himself to the tennis world on the hard courts of Washington in August 2007, storming into the final of what was then the Legg Mason Tennis Classic by winning five consecutive third-set tiebreaks.

The 6-foot-10 Isner was ranked No. 839 in the world at the time. And the most notable thing about him, other than his height, was a serve that packed an even greater punch than that of the top-ranked American of the day, Andy Roddick.

Roddick retired at last year’s U.S. Open, and Isner has supplanted him as the No. 1 American. But in six years, little has changed about Isner’s penchant for tiebreaks.

On Wednesday, he advanced to the Citi Open’s third round by defeating fellow American Alex Kuznetsov, 7-6 (7-2), 7-6 (7-4), in the first meeting of their careers.

As the tournament’s No. 8 seed, Isner had the benefit of a first-round bye. And it was welcome given that he contested a hard-court final at Atlanta on Sunday, saving two match points against Kevin Anderson en route to another close victory.

A native of Greensboro, N.C., Isner leads the men’s tour with 558 aces. He tallied 95 alone in Atlanta last week. But because he lacks a strong return game, he typically struggles to break serve. The result lands him in an inordinate number of tiebreaks.

With so much experience in the format, Isner has learned not to stress when a set is deadlocked at six games each.

“I won four matches last week that were super tight,” said Isner, an ice bag lashed to his right knee. “I could have lost all of them. I could have lost today. I just try to focus. And I play pretty well in the tight moments. Having my weapon — my serve — and being able to get free points puts pressure on my opponents.”

Despite any weariness, Isner was cheerful following the victory, fielding questions about everything from the sport’s recent drug suspensions to his decision to pose nude for ESPN The Magazine’s body issue.

“It’s something that a few years ago, I never would have thought of myself doing,” Isner said of the strategically posed photograph. “I’ve just become more comfortable with who I am. Being such a big guy, I’ve learned to accept that from my height, I’ve been able to do a lot of cool things on the court.”

As for the recent doping sanctions in sports, Isner said he felt tennis was “clean,” owing to its frequent drug-testing. He once was tested twice in the same day, he noted.

Also advancing Wednesday was American Mardy Fish, who defeated Julien Benneteau of France, 6-3, 7-5. Fish only recently has returned to competition after having a heart arrhythmia diagnosed last year. And he’s keeping himself busy, competing with Radek Stepanek in doubles, as well.

Note: With heavy rain bringing a halt to the proceedings shortly before 8 p.m., the evening’s women’s matches were postponed until Thursday. At that point, 12 of the 16 men’s second-round matches had been completed. Officials tried multiple times to resume play, but each time the courts were nearly dry, rain returned.

Play was suspended for the night at 11:35. Eight men’s players will have to complete two matches in one day to get back on schedule, including the top two seeds, Juan Martin del Potro and Kei Nishikori, neither of whom has struck a ball yet in the tournament.