UNIONDALE, N.Y. -- Sebastian Korda felt a thrill as he walked into through the halls of the cavernous Nassau Veteran's Coliseum last week and saw the enormous posters paying tribute to the team that once made the arena famous, the New York Islanders.
"It has so much NHL history, it's really cool," Korda, the No. 1 junior in the world, said at this week's inaugural New York Open. "The stadium even feels like a hockey arena; it's pretty awesome to be here."
There was a time when Korda, 17, dreamed of skating away most winter evenings in an NHL uniform instead of playing tennis in arenas much like this one. Starting at age 3, he was a rink rat who skated five days a week and played for a team that was ranked second in North America junior hockey in his age division.
Then an odd, utterly unexpected thing happened.
At age 9, Sebi accompanied his father, Petr, the former Australian Open tennis champion and then Radek Stepanek's coach, to the 2009 US Open. Sebastian grew enthralled watching Stepanek lose an entertaining night match to Novak Djokovic. According to Petr Korda, when Sebastian returned home to Bradenton, Florida, he declared, "Dad, mom, I don't want to play hockey anymore. I want to play tennis."
"I kind of listened to my heart," Sebastian told ESPN.com on Monday. "I fell in love with tennis, with the atmosphere and excitement at that match, and I saw myself doing that for rest of my life."
Perhaps the most exciting and certainly most thrilling part of that longed-for life began Tuesday night at this ATP 250 event, where Korda played his first tour-level match. A wild card thanks to his recent win in the Australian Open junior event and rise to No. 1, Korda took the first set from celebrated 20-year-old Frances Tiafoe before a few rookie mistakes and his lack of physical strength allowed the muscular Tiafoe to prevail in a puppy-eat-puppy battle, 4-6, 6-4, 6-2.
Among the interested observers in the sparse opening day crowd was tennis icon John McEnroe. His first word when asked what he thought of Korda was, "Wow."
"He's going to be an incredible player," McEnroe told ESPN.com. "He hits the ball just beautiful. He has great touch and he already moves really well for a big skinny kid who still isn't very strong."
Korda is 6-foot-4 but weighs a mere 165 pounds, stats that immediately evoke memories of the nickname once bestowed on Petr, "the human toothbrush."
Sebastian's decision to drop hockey cold (he hasn't skated since taking up tennis) was a curveball worthy of Clayton Kershaw. But neither Petr Korda nor his wife, Regina Rajchrtova, who once was ranked as high as No. 26 in the world, flinched. All three Korda children were precocious athletes, encouraged from the start to explore all sports. (Two girls, Jessica and Nelly, are pro golfers.) As Petr said, "Ice skating, taekwondo, golf, skiing, hockey. We did everything, everything except ballet."
Hockey's loss became tennis's gain. But not without some anxious moments.
"We told him, 'It won't be easy. You're almost 10 and a lot of kids are already ahead of you.'" Petr said. "But we also knew that if he really loved it, he would catch up."
With his parents as his primary coaches, he quickly morphed from gifted, if casual duffer, into an elite junior. The game plan was strikingly counterintuitive, in that it lacked a sense of urgency. "We have a little different philosophy," Petr said. "Until last year at the US Open, he was the kid who didn't play twice a day, just once."
Dean Goldfine, a USTA player development coach, assists Petr and often travels with the family. "Petr was great about not worrying about results," Goldfine told ESPN.com. "Sebastian didn't travel all over the place. For them, it was all about loving the game and working hard."
Another odd, somewhat unexpected, thing happened at the end of last year. Sebastian set himself a goal. He decided to win the 2018 Australian Open junior title to celebrate Petr's 50th birthday on the 20th anniversary of his singles championship in Melbourne. And why not? One Korda kid had already bagged an Australian Open: Jessica Korda, now 24 and ranked No. 24 on the LPGA Tour, won that golf event when she was just 18 (sister Nelly, 19, is ranked No. 64 by the LPGA).
It was still a brassy call, given that Sebastian hadn't won more than two matches in the handful of junior Grand Slam events he had entered before he ran the table in Melbourne. Clearly, family affection and loyalty are powerful inspirational forces in the Kordas.
"Jessica is more of a mother figure to me, because she's about seven years older," Sebastian said. "Nelly, we're just best friends. If we do fight, it's rare. We hang out a lot and have friends in common."
Sebastian also always makes a point to remind journalists of his mother's accomplishments, as well as the role she played in shaping his game. He isn't just being a good son; if his ball-striking seems a paternal legacy, his height and mellow, gentle temperament are evocative of his mother. He said, "When my father was traveling with Radek, it was my mother hitting with me and helping."
The days when Petr could thump his son on the court are long gone. A son's first victory over an accomplished parent is often a developmental landmark, but it's one Sebastian has avoided. The two never play sets. Sebastian knows he can beat his father but, as he put it, "I don't want to."
Apprised of the remark Petr allowed a smile. His own father was a top-30 player back in what was then Czechoslovakia, and Petr didn't want to beat him either as he improved. "My father let me be under his wing -- I knew that," Petr explained. "When it was time, he let me fly. That is what I am trying, too."
Although lean, Sebastian seems perfectly built for today's game, which is similar to 20-year-old world No. 4 Alexander Zverev. Both are nimble for taller men, capable of preemptive serving, and just as content to crack punishing groundstrokes from the backcourt as to attack.
Sebastian didn't just ride his natural talent to the junior title in Melbourne in January. "What clicked for me was a lot of hard work in offseason," he said. "It helped me a lot. I was having more fun on court because of that."
That "work" included more intensive practice and a heavy diet of Futures and Challenger events starting after the last US Open.
"He had good results," Goldfine said. "Success at a higher level helps you gain confidence. He's grown [physically] a lot. He's getting stronger. It takes time."
Even if he no longer has any future in hockey, Sebastian looks primed to score big on the tennis court.