Serena Williams turned 35 this past Monday.
As a belated birthday present for her legion of fans, we offer these fun facts:
Roger Federer, Martina Navratilova, Margaret Court, Pete Sampras and Chris Evert -- who combined to win 101 Grand Slam singles titles -- took home a total of one after their 32nd birthdays. That late-in-life breakthrough belonged to Navratilova, who was 34 when she won Wimbledon in 1990.
For the record, Williams, who for years has been defying the laws of nature that usually ground 30-something tennis players, has won five majors since turning 32.
After her second consecutive surprising exit in the US Open semifinals, when Serena failed to win her 23rd Slam, which would have broken a tie with Steffi Graf and set an Open-era record, her coach, Patrick Mouratoglou, was already looking ahead.
"I know people are going to be very much focused on the 23rd," he recently told CNN International's Ravi Ubha at the grand opening of his new tennis academy in France. "I'm more focused on the 30th.
"Why not set up a record that will never be beaten in history? I think she can do it."
Why not? Clearly, this was a slice of bravado from a coach seeking to take pressure off his athlete as the 2017 season looms.
But the questions raises itself: How many more majors will Williams win before she decides to walk away from the game? It's a favorite parlor game these days among tennis aficionados.
ESPN.com unscientifically polled more than a dozen tennis experts, a number of them former players-turned-analysts, and the average over-under was between two and three Grand Slam titles.
More than one, however, believes the number is zero.
"My gut feeling is that she's done," one respondent said. "That's really based more on her emotional/mental attitude and reactions than anything else. I have a hard time seeing her going back to the drawing board, refilling that tank, focusing on what she does best."
More typical was this response from Pam Shriver:
"I think she will win three more," said the 21-time Grand Slam doubles champion. "Wimbledon, and at least one more on hard courts. But I don't see them coming in bunches as they once did. The only one that can put a big crimp in that is the new No. 1.
"I would guess that Serena still has a better chance to add to her [Grand Slam] count than Roger, Rafa, Maria or Vika. But this spinning planet slows for no one." Mary Carillo
"I think [Angelique] Kerber's in that conversation. With a good next six months, she can establish herself at the top."
After failing to win a major in nine previous seasons as a professional, the 28-year-old German won two this year and supplanted Serena as the WTA's No. 1-ranked player. She beat Williams in the Australian Open final and lost to her in Wimbledon's championship match.
Based on the 2016 returns, it appears Kerber has the best chance to prevent Williams from catching or surpassing Margaret Court, who has the all-time record of 24 major titles.
Going back to Wimbledon in 2012, Serena has won half of the major titles available, nine of 18. The only woman with two over that time is Kerber. The others still active are the tandem of Garbine Muguruza and Petra Kvitova. Flavia Pennetta, Marion Bartoli and Li Na have all retired. Maria Sharapova is serving a drug ban, and Victoria Azarenka is pregnant with her first child.
If (and when) Sharapova and Azarenka come back, that could complicate the situation, for they are still potentially viable at 29 and 27, respectively. Karolina Pliskova, 24, who beat Serena in this year's US Open semifinals, is another likely threat.
In losing that straight-sets match to Pliskova in New York -- and to Roberta Vinci at the same stage in 2015 -- Serena's nerves were on display, a phenomenon that often visits older players. And for much of the 2016 season, Serena was dogged by shoulder and knee injuries.
"The only person to win a Slam at 35 or older is Ken Rosewall, and he did it three times," said Brad Gilbert, who coached Andre Agassi, Andy Roddick and Andy Murray. "That said, never, ever underestimate a Williams. If you don't think she can do it, she'll say, 'I'm going to show you that you don't know me.'
"Fast-forward to 2018, and if you tell me she has three, I'd be less surprised by that than if she had won none. The next year is a big year for her. If she's successful, she continues on. If she doesn't, who knows? Just the fact she's in this position at her age is outrageous."
Paul Annacone, the longtime coach of Pete Sampras and a Tennis Channel analyst, is optimistic.
"There's no reason next year can't be as good or better," Annacone wrote in an email. "It's about her desire and the ability to play enough so she peaks at majors -- but not too much to where she is burnt out entering them."
Serena has taken a breather after the US Open the past two years. Last season, she stopped playing entirely, but this year it's not clear if she'll play the WTA year-end event in Singapore after passing on the Wuhan Open and China Open.
Shriver feels strongly that she should play.
"Sure, there will be a focus on the Slams, but you need a couple of tournaments to tee you up," Shriver said. "You can't just rock up to the Slams and be your best -- not even Serena. I think Singapore is really important to play because it guarantees her three matches at minimum -- and probably four to five.
"If she shuts it down like last year, I'm not going to pick her to win the Australian Open."
Mary Carillo, a broadcaster for Tennis Channel and NBC, agrees with the concept.
"When Serena returned to the tour this January, she still didn't seem as fit and refreshed as she needed to be," Carillo wrote in an email. "Fitness/focus/motivation is now on the Compulsory Serena Checklist.
"More important than the physical fitness of the 35-year-old is her mental fitness, and nothing wears down the fortitude of athletes more than the ravages of time and injury. The supreme effort and commitment it takes to want it all over again? Only Serena knows how much she is willing to continue to give."
Carillo wonders if she might find motivation in the continuing success of her older sister Venus, who reached the semifinals at Wimbledon at age 36.
"Her big sister seems to find much more joy in the journey," Carillo wrote. "Maybe Serena draws inspiration from Venus. It could help her surpass Graf and add a few more major titles.
"I would guess that Serena still has a better chance to add to her count than Roger, Rafa, Maria or Vika. But this spinning planet slows for no one."