'That's a woman thing,' Chris Evert was saying the other night. Evert was talking about the bond between her and Martina Navratilova, which grew only stronger as they played each other an incredible 80 times. Eighty times. Between the two best players of their age. This sense of awe goes way beyond nostalgia into a sense of wonder over glory days when two charismatic giants graced the courts. There has probably never been a friendship between rivals to match the one between Evert and Navratilova. Their relationship has been touchingly captured in a documentary, 'Unmatched,' for the ESPN series 30 for 30,which will be shown Sept. 14. As the U.S. Open begins Monday, both women remind us to see the big picture, to acknowledge our colleagues and even our competitors, to tap our racket over somebody else's shot, to respect the other, whatever the other may be. Chatting before a preview in New York, Evert said the 'woman thing' came from Billie Jean King, who convinced younger players they had a stake in building women's tennis. Evert does not take credit, but she also brought the ethics of her family into the locker room, where she smiled (maybe to intimidate, but also to greet) at the newcomer from Czechoslovakia. At that first tournament, in 1973 in Akron, Ohio, Evert looked through the recently acquired pounds and saw the athlete who could beat her. In the documentary, Evert takes a deep breath and confides to the camera that Navratilova, at her best, was better than Evert at her best. It takes Evert-like guts to make that admission. She also won 37 of their 80 meetings. They are constantly in touch -- sometimes in the middle of the night, when either needs a supportive ear or shoulder. The documentary does not mention that Navratilova recently had a bout with breast cancer or that she is training for a December hike up Mount Kilimanjaro; it alludes to Evert's three divorces. These two peripatetic women always promised each other that they would sit down someday and have a glass of wine and open up to each other. To a very satisfying degree, the producer Hannah Stormand the directors Nancy Stern Winters and Lisa Lax (twins who grew up idolizing both players) popped the cork and let the cameras roll. Some of the revelations are touching. Navratilova looks at Evert and recalls that as she came to grips with her sexuality, Evert was, in her words, gay-friendly. Navratilova thanks her. On Sundays, they were often the last women left, dressing in the same locker room, arranging practice together, lunching together -- and going out to play a final, 60 times in 16 years. Afterward, the winner would be careful of the loser's feelings. For many years, they would then travel together to the next tournament. Imagine that. 'Before I even met her, she stood for everything I admired in this country: poise, ability, sportsmanship, money, style,' Navratilova said in her autobiography, 'Martina,' published in 1985. In the book, which I co-wrote, Navratilova raved about Evert's mother, Colleen: 'From the first time I appeared on the tour, I got the feeling she honestly felt bad when I lost and happy when I won.' The two players recall the time in the early '80s when Nancy Lieberman, the great red shark of women's basketball, convinced Navratilova that she had to feel hostility toward her major opponent. They got through it. Male athletes, by contrast, are much more catty. Witness the disdain between Jimmy Connors and John McEnroe and the way Andre Agassi dissed Pete Sampras in his recent book. Bill Russell and Wilt Chamberlain did stay respectful, even when Russell won the titles, but Joe Frazier still hates Muhammad Ali for calling him a gorilla in the flammable rhetoric of their time. I used to think the two women were wise enough to know they needed each other in their athletic old age, which, in a fractious world, is no small thing. But the documentary convinced me that Evert and Navratilova were closer than I had realized. They drive around autumnal eastern Long Island in a convertible, an athletic Thelma and Louise, telling good stories on themselves -- or each other. In her sardonic burlesque-queen tone, Evert recalls being single and ogling Dino Martin, handsome son of Dean. To Evert's chagrin, Dino asked her if he could get a date with Martina because he liked her buff physique. They eventually went on a double date, where apparently nothing happened; Navratilova explains that she was still figuring herself out. Evert rolls her eyes, suggesting that after a chaste date with Dino, her pal could have figured it out. Evert then tells how Navratilova returned the favor by introducing her to a handsome skier named Andy Mill, who escorted a panicked Evert down a steep trail in Colorado. He was so gallant, Evert married him -- for 18 good years, she adds. Evert also thanks her buddy for lending her Aspen bedroom for Evert's first tryst with Mill. That's what friends are for, right? The documentary also shows artful passing shots and acrobatic volleys, steely glares and emotional meltdowns, all over the tennis globe. 'Unmatched' takes nothing away from today's tennis, while acknowledging that there was never anything quite like Chris and Martina. 