CANCUN, Mexico -- Chris Evert had a confession. She couldn't remember the first time she met Martina Navratilova, the woman who would go from being her fiercest rival to greatest confidant. 

She was too busy trying to win a game of backgammon.

"I remember better than Chris I think, because for her I was just some youngster walking by," Navratilova said at a media conference at the GNP Seguros WTA Finals Cancun. "But she did say hello. But she had no idea who I was. 

It was in Fort Lauderdale, Florida in 1973, Navratilova's first-career tournament. "The S&H Green Stamps, the USLTA tour -- because I was not allowed to play the Virginia Slim Tour, which was what I really wanted to play, but the federation wouldn't let me," Navratilova said. She navigated the qualifying draw to earn her first main draw appearance.

While strolling along, she spotted Frank Hammond, the veteran umpire whom she believed also officiated at the tournament. Evert was there, engaged in a game of backgammon. Navratilova, who recalled first reading about Evert's existence in an issue of World Tennis Magazine when she was 12, offered a casual greeting and kept going. 

What followed suit was a prolific rivalry that took the women's game to the next level. The Evert-Navratilova rivalry was a two-woman show. They faced off 80 times -- 60 of which came in tournament finals -- and left their lives intertwined to this day.

"I think the moment we became really good friends was the moment we realized that something was bigger than ourselves individually," Evert said. "I think you and I looked at each other after, like, 50 matches. We're like, 'Whoa, look at that crowd.'"

Chris Evert World No.1 Trophy

After the dust settled on their careers, splitting 36 Grand Slam titles between them, their competitive ferocity transformed into an unbreakable, enduring friendship. In January of 2022, Evert was diagnosed with Stage 1C ovarian cancer. One of her first calls went to Navratilova.

When she got off the phone, Navratilova went to her jewelry box and put on a Cartier necklace that Evert gifted her for her 60th birthday. Then, in December 2022, Navratilova was diagnosed with Stage 1 breast and throat cancer

"We were always in the trenches when we played matches, and then we're in the trenches when we had cancer together," Evert said. "We'd laugh about that." 

Tennis may be an individual sport, but it takes two to fashion a compelling rivalry. Whether it was the ATP's Big Three or the box-office showdowns between the Williams sisters or Serena vs. Maria, rivalries are the spark the sport thrives on. 

Each woman credited the other for unlocking levels in their games and physicality they did not know existed. Evert was the benchmark that Navratilova relentlessly pursued. When Navratilova supplanted her at the top of the game, it was Evert's turn to go back to the drawing board. For the first 12 years of the WTA rankings, they were the only two women to finish as year-end No.1s.

"I think you need quality of players and uncertainty of who's going to win," Navratilova said, "but you also need the one-on-one conflict that people get excited about. You see on social media, some of the fans, oh my god, they are all in. It's like a cult of personalities."

Surveying the current landscape on tour, Navratilova sees the next big rivalries already bubbling up. 

"We have a bunch of players that are kind of similar age, and moved up in the same time with Elena Rybakina, Coco Gauff and Iga Swiatek and, of course, Aryna Sabalenka," she said. "That's the core. Then you have Jessica Pegula, Maria Sakkari, all these women nipping at their heels where the way this tour is structured, I think you'll see them playing each other more often." 

Aryna Sabalenka Iga Swiatek WTA Finals 2023

WTA/Jimmie48

New installments of the Swiatek and Gauff and the Sabalenka-Rybakina rivalry have already been renewed in Cancun this week. While semifinal qualification still hangs in the balance, No.1 Sabalenka and No.2 Swiatek could meet for a third time this year, potentially with the year-end No.1 on the line.

"I think Martina brought her own set of fans to the table, and I brought my own set of fans to the table," Evert said. "Even the fans were at each other in the audience. 

The rivalry between Evert and Navratilova was intensified by their contrasting styles and the differences in their personalities. While Navratilova often displayed her emotions openly during matches, Evert maintained a more composed demeanor.

Additionally, their backgrounds could not have been more divergent, with Navratilova hailing from a communist nation and Evert growing up in the United States. It was this stark contrast that caught the public's attention.

"We brought more eyeballs to the TV and to sports pages and I think that was great," Evert said. "I'm a big fan of rivalries."