John Isner cites two major reasons why he's playing his best tennis this season at the age of 33.

Hard work and marriage.

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Fresh off his fifth Atlanta title on Sunday, Isner continues his summer surge.

The Miami Open champion denied two match points defeating Ruben Bemelmans en route to his first Grand Slam semifinal at Wimbledon, where he rocketed a tournament-record 214 aces.

Isner, who wed long-time fiancé Madison McKinley on December 2nd, says marriage has given him greater life perspective that's translated to less tennis stress.

"It's definitely settled me down," Isner said of marriage. "I think it's made me worry less about tennis. Because a lot of times it's consumed me the last six, seven, eight years because it was the most important thing I had going. But now, it's not."

The second-seeded Isner, who will play wild card Noah Rubin in his Washington, DC opener tonight, said personal joy has given him more positive perspective on court.

"I think it definitely takes some pressure off of me in a sense," Isner told the media at the Citi Open. "My most important thing is now starting a family and raising a very, nice polite daughter with my wife. That's number one on my list.

"Tennis is really just secondary. Of course, I want to do this really well. It's super important to me. But there are some more important things going on in my life and I think that's helped my tennis game, for sure."

The Isners are expecting their first child, a baby girl, in September.

"Yeah, our baby is due on September 22nd, so hopefully after a nice run at the US Open, you know, we'll see what happens," Isner said. "Our first kid, sometimes they come early, sometimes they come late. Whenever it comes, it's going to be a blessing.

"Madi and I are certainly looking forward to that. And our life is in Dallas now. That's where I live. We're going to have a lot of help, which helps, because my in-laws, her parents are amazing. Her family is amazing. And then my family I think is awesome, as well. So this kid is going to have a lot of love. That's for sure."

Photo credit: John Isner Instagram