By Joe McDonald

NEW YORK—It’s hard to believe, but since Andy Roddick retired, John Isner is still the top American.

Even though it may be more of a statement about American men’s tennis, rather than Isner’s exploits, it’s still impressive.

US Open: Pliskova Working With Conchita Martinez

“I have been the top American for, I think, five, six years,” Isner said today after launching his 13th Open with a straigh-sets win over Bradley Klahn. “Good chance I can finish top American this year, as well.

“So, you know, I think it just goes to show that, you know, how the landscape of our sport is changing, and players into their 30s can still be doing very good things. That's definitely the case for me.”

At 33, Isner is probably playing his best tennis of his career.

Fresh of the historic Wimbledon semifinal loss to Kevin Anderson that propelled him to a career-high rank of No. 8 last month, Isner beat compatriot Ryan Harrison to launch his summer hard-court season winning his fifth Atlanta title.

The former all American at Georgia struggled after that falling to 152nd-ranked Noah Rubin in Washington, DC and 80th-ranked Pierre Hugues-Herbert in Toronto before bowing to Sam Querrey in Cincinnati.

Undaunted, Isner played controlled tennis swatting 20 aces in today's 7-6 (3), 6-3, 6-4 sweep of compatriot Klahn.

“You want to be as relaxed as you possibly can,” Isner said. “I think today I was, because given the conditions, how hot, especially muggy it was, for me in particular I couldn't waste any emotional energy out there.

“There were some times in the first set I was a little bit frustrated and wasn't quite finding my game, but I just knew I had to stay as calm and collected as I possibly could, because the conditions were very tough.

“But I need to do that in all my matches. So that, you know, being calm and having clarity on the court goes hand in hand with being rested, as well.”

That might be the difference between Isner today and five years ago, where he may have imploded when he lost focus. Now, he seems more zen and mature, ready to take the reigns of the tough matches.

“I think once Wimbledon ended,  I mean, I was home in North Carolina afterwards, and I knew the match was on TV. I didn't watch it. You know, it's tough,” he said. “You know, it's a weird thing in tennis. When you lose and you go home and then match you could have been playing is on TV and a big one, you definitely don't want to watch it.

"I watched a rerun of the Rose Bowl, which gave me much better feelings. I think once that ended, I felt like I actually did a pretty good job of getting rid of that memory pretty quickly.”

That’s why you can’t count out the No. 11 seed in the Open.

Although it’s been 15 years since Roddick defeated Juan Carlos Ferrer as the last American man to rule the Open, Isner still believes in possibility.

You saw him make runs before and now, he could do it again.