Chris Evert showered love on her 'great friend' Martina Navratilova, who turned 69 on Saturday, October 18. The two icons have always shared a strong bond, even when they were each other's biggest rivals during their playing days.Evert and Navratilova boast the biggest tennis rivalry, men and women, in the Open Era. Between 1973 and 1988, they squared off against each other 80 times, including 60 title clashes. The head-to-head record ended 43-37 in Navratilova's favor.On Saturday, Evert posted a photograph alongside Navratilova on Instagram and penned a heartwarming message that read:"Happy Birthday to my former rival, current great friend @martinanavratilova. Wishing you lots of joy and love in your life going forward, because with a heart as big as yours, you deserve it!❤️🙏😇." View this post on Instagram Instagram PostChris Evert won 18 Grand Slam titles and spent 260 weeks as the World No. 1 before retiring in 1989. On the other hand, Martina Navratilova was the top-ranked player for 332 weeks. The Czech-American also won 18 Majors and played her last singles match in 1994 (last doubles match in 2006).Martina Navratilova weighed in on her friendship with Chris Evert at 2025 Tennis Hall of FameMartina Navratilova and Chris Evert at the 2024 French Open - Source: GettyAt the 2025 Tennis Hall of Fame in August, Andy Roddick interviewed Martina Navratilova and said he was 'obsessed' with how she forged a lifelong friendship with her biggest rival, Chris Evert.Navratilova spoke about her relationship with Evert and revealed whether they communicated regularly."We call here and there, and we text. Usually, we're sending each other tips on what shows to watch on Netflix. We connect, and we're doing a documentary, actually, that'll be out hopefully early next year. It's on our relationship and our rivalry," Navratilova said at 31:45 (via Served with Andy Roddick).Sharing her thoughts about their rivalry, the former World No. 1 said:"It had all of those aspects of it: the respect, the like, the hate, the rivalry, but most of all, the respect that never went away. And empathy, I think we were always very empathetic to each other. So many times when you see our handshake, you don't know who won the match because we're both smiling."Martina Navratilova also recalled the 1978 Wimbledon final, where she defeated Chris Evert for her maiden Grand Slam title."When I won my first Wimbledon, Chris was so sweet. It was just overwhelming. She was happy for me even though she lost. If I had to lose to anybody, I'd rather lose to Chris than anybody else," she said.