And this week, she became one of the most experienced, winning her 19th and 20th Grand Slam titles at the US Open, first a mixed doubles title with India's Leander Paes on Friday and on Sunday a doubles title with Sania Mirza, also of India.
In a swift 70 minutes Sunday, Hingis and Mirza, who were the top seeds coming into the women's doubles competition, defeated fourth-ranked Casey Dellacqua of Australia and Yaroslava Shvedova of Kazakstan, 6-3, 6-3. All told, Hingis, who turns 35 later this month, won five Grand Slam titles this year, a significant collection of hardware for a player who at several points in her career had assumed her life as a tennis player was over.
"It feels like it's doing it all over again," Hingis said after her match Sunday, a US Open towel draped over her shoulders. "It's like I don't think about, OK, last time it was 18 years ago. It's what counts for me is right now, today in this moment. I know I have the support and the trust that I have for her shots and for her game. It's even building up every time we step out together."
As more and more women in tennis have longer careers, Hingis' successful second act in doubles may be a road more of her fellow racket-wielding professionals will take. With five Grand Slam singles titles to her credit, Hingis was also early to embrace the doubles side of the game, winning her first doubles slam in 1996 at Wimbledon, and when she won the singles title a year later at the Australian Open, she was the youngest Slam singles champion ever. However, injuries, the plague of many a tennis star, took their toll, and Hingis started and stopped her career at various points. She dabbled in coaching, then returned to tennis as a doubles specialist. Sunday, she was quick to dismiss any notion she would return to singles.
"No, thanks," Hingis said. "I was just practicing yesterday and I almost hurt myself. 'Oh, my God, it's a long season, hard-court season.' We play six weeks in a row. I have [to] still play also Team Tennis. I'm turning 35 at the end of the month, so I just keep it that way. I'd rather win alongside Sania and Leander Grand Slam titles than having to struggle with my body."
Mirza and Hingis began playing together in March and at first were befuddled by how terribly they practiced together.
"We had the worst first practice ever, ever," Mirza said. "We played, and we were like, 'Oh, my God, we cannot play together.' We won one game I think out of 12. We were like, 'Maybe not.' Then, 'Yeah.' "
Any mismatch didn't manifest in competitive play. Mirza and Hingis won the women's doubles title at the BNP Paribas Open at Indian Wells and again at Wimbledon. They breezed through the tournament here, never losing a single set.
"They're the best team in the world," Casey Dellacqua said Sunday. She added, "Our expectations were that it was going to be a hard match."
"Separately, they were very good doubles players," Shvedova said. "And they found each other this year."
In the six months or so they've played together, Mirza and Hingis have grown from acquaintances, and sometimes singles opponents, to friends, Mirza said, a demeanor that helped them win their US Open title.
"I think we trust each other on and off the court," Mirza said. "I think that helps us through a lot of tough moments on the court. Obviously our games match, you know, kind of complement each other, so to say, you know, with her at the net and from me at the back."
It's a breeziness that allowed Hingis to smile the handful of times she floundered at the net and help Mirza shake off whenever she did the same. Although they later confessed to being nervous heading onto Arthur Ashe Stadium on Sunday afternoon, the last draw there before Novak Djokovic and Roger Federer played the men's singles final, it didn't show with their vibe on court mirroring the casual tone of their practices and earlier matches on the outer courts.
"The way Sania was playing the last three, four matches," Hingis said, "it was just incredible. She was hitting bombs from the baseline, and I was able to, the last two matches, pick it up and hit some good volleys to finish it off."
Hingis added, "We don't even have to, like, suffer. It was like a pretty convincing match. It works well."
After the victory hugs were exchanged, the flags of India and Switzerland paraded across the court, the smiles gleaned before cameras, Mirza and Hingis chatted in the windowless, cinder-block hallways of the underbelly of Arthur Ashe Stadium about their respective schedules of handshaking, trying to sneak time in with family, then had more tournaments together in China and Singapore. Both of their phones were exploding; Mirza noted her match would have aired in the evening in India, a prime-time event.
"We can celebrate then," Mirza said of their trip to China. "We don't really have the time right now!"
Hingis said she was planning to stay in Queens, New York, for a while longer to watch what she could of fellow Swiss star Roger Federer's battle for the men's singles title but had a flight Sunday evening to Europe and then Mirza to India.
"All of this today, I think is incredible," Hingis said. "It's a tremendous bonus in my career of tennis."