John Isner retired from professional tennis after playing at the U.S. Open, bringing an end to a career that included one Grand Slam semifinal appearance and a victory in the longest match in the sport’s history.

At 6’10, the former professional tennis player is hard to miss. His serves on the tennis court are tough to return and are legendary.

It has been a little over a month since the Dallas resident hung up his racket to spend more time in Dallas with his young family.

NBC 5 caught up with Isner on a local tennis court playing for fun with his son Hobbs, the first time he’s held a racket since his last match at the U.S. Open more than a month ago.

“I’ve gone on the court with my son and he’s so young, where I’m still kind of hand-feeding him the ball,” Isner said.

The 38-year-old American tennis star who wowed fans around the world with his signature serve, powerful groundstrokes and quick hands says retiring was emotional but it was time for the next chapter.

“Being as big as I am, I think it finally caught up to me. I mean, it took a big toll on my body.”

Isner is the career ace leader in the history of the men’s tour but is perhaps best known for the marathon match at Wimbledon.

“The one match everyone talks about in 2010, I will never, ever forget that match, even though I might want to. 11 hours and 5 minutes in 2010. I don’t want to call it a fond memory because it wasn’t that much fun playing in that match. It was just a war of attrition out there. But being a part of it, looking back on it was very cool,” Isner said.

Isner won it.

As he looks to the future, he says his time will be mostly spent in Dallas with his wife Maddy and four children, ages five and under.

“Definitely as it stands right now, I have more time than most dads. So I am taking them to school, taking them to practice, taking them to their games,” said Isner.

It is a role reversal in the Isner home as his daughter and three sons grew up watching him play on the pro circuit.

“I think the older two will remember. We’ve made some incredible memories with everyone. You know, this year we went to Australia with the whole family. The whole crew also went to London and then last year we did Madrid, Rome, Majorca and Paris with the whole family,” said Isner. “It’s going to come full circle with me. I mean, having the family that I have now, I know that’s going to be me, who knows what my kids get into sports-wise.”

You will also catch Isner playing in Dallas visiting sick children at Children’s Health.

“You go there and you visit and it breaks your heart, really. But these kids are so strong and Children’s (Health), they’re the best, ” he said 

A few years ago, John and Maddy together established the Isner Family Foundation, assisting families at Children’s Health financially. Brent Christopher, the President of the Children’s Health Foundation says the Isners like to show up, too.

“Sometimes it’s a little dramatic to see someone as tall as John walk through the door of your hospital room. But when they understand that one of the world’s best athletes, who happens to live in your hometown is coming in to hear your story and wants to let you know that the community cares about you and is with you and supporting you in whatever fight you are having to take on. That means the world,” Christopher said.

Between these children and his own, Isner says his plate will be full and he walks away from tennis with enormous gratitude.