It is a sports rivalry and friendship the like of which may never be seen again.
Chris Evert and Martina Navratilova met a grand total of 80 times on the tennis court, with Navratilova finishing with a 43-37 advantage.
Somewhere between their first meeting in Akron, Ohio, in 1973 and the final encounter in Chicago in 1998, they forged a relationship that flourished despite all the forces of competitive sport that could work against it.
It continues, more than 37 years since Evert won that first match against a chubby 17-year-old from the-then Czechoslovakia.
To put it in today's context, Serena and Venus Williams, at their current rate, would have to play to play for about 34 more years to reach 80 matches played against each other.
There has been nothing more unexpected and sobering in the Evert-Navratilova relationship than Navratilova's diagnosis with breast cancer this spring.
"What? The seemingly healthiest, fittest woman in the world," is how Evert, 55, described her reaction to the news about Navratilova, 53.
"I've just been there for her, but I think she has a lot of people there for her. She's kept me up to date. At the French Open [where Navratilova was doing Tennis Channel commentary] the first bout [of radiation]she was feeling nothing. With the second bout, she was exhausted. Then she still went out and won the [French Open veteran doubles]tournament. And her cancer is gone now."
Evert turned reflective. "We're over 50, we're at that age. It's a different stage in our lives. We're not free-wheeling 20-year-olds, swinging our racquets and going through life with not a care in the world any more. It's scary."
Appropriately, Evert and Navratilova finished with an identical 18 Grand Slam singles titles. "We're better friends now than ever, because we're not competing," she said. "We text each other or e-mail each other all the time. We're always talking about our personal lives and what's going on."
Known as the icy-cool competitor to the more combustible Navratilova, Evert laughs when she concedes, "we're probably more alike than we'd care to admit."
The two had a relationship that was rare considering they were dominant players in an individual sport. "I remember staying with Martina in Aspen," Evert recalled about the late 1980s. "This was our schedule: we would ski from about nine o'clock to two o'clock, then we'd go and play tennis from three to five and then we'd go right to the gym from five to seven.
"That was her schedule, so I kind of blended in because I was staying with her. I remember looking at her and I'm like [moving her arm up as if doing a curl]15 pounds and she's [lifting]35 pounds. I'd joke, 'Martina, I'm doing everything you're doing and my body isn't remotely close to yours.' But I'd laugh, because I got the most out of my 5-foot-6 body."
Evert is still super-fit, hitting almost daily in the winter with students at the Evert Tennis Academy in Boca Raton, Fla., where she is the majority owner.
She claims she has had "no injuries," before noting, "but I still play on clay a lot."
The woman who has the highest career match winning percentage in history, .900 (1309-146), said, "it's a freak thing that I've never had surgery."
These days she looks after her three sons, Colton, 14, Nicky, 16, and Alex, 18, the latter set to start college at the University of Colorado.
"I've really kept them away from tennis," said Evert, who is single again after the break-up of her marriage to golfer Greg Norman last year. "They're all skateboarders, surfers, all the X-games like their dad [her second husband Andy Mill, a former American Olympic skier] They're fearless like him, not like me."
That is only partly why she declined a recent invitation from Navratilova. "She invited me to climb Kilimanjaro [in Tanzania]with her in December and I said, 'What, are you nuts?' " Evert said. "And she goes, 'Why not?' And I go, 'Martina, I've got three kids, I don't have time to train.' Then she says, 'You don't have to train, you're in great shape.' I said, 'Martina, it's what, 16,000 feet, I'm bad at altitude?'
"She's ready to conquer everything."