Chris Evert looked back on her tennis career as Billie Jean King marked the 51st anniversary of the WTA introducing its first official rankings and Evert becoming the first-ever World No. 1 in women’s tennis.

On Nov. 3, 1975, Evert became the first World No. 1 in women’s tennis after the Women’s Tennis Association launched its computerized ranking system. The American had already established herself as one of the sport’s leading players through her remarkable consistency.

By then, the 20-year-old had won four Grand Slam singles titles. She captured the French Open and Wimbledon in 1974, defended her French Open crown in 1975, and claimed her first of six U.S. Open titles that September. Her achievements also included a 125-match winning streak, further cementing her place at the top of the game.

To mark the anniversary, King shared several pictures of Evert on social media on Tuesday, celebrating her achievement. She wrote:

“On November 3, 1975, 51 years ago today, @chrissieevert became the first-ever No. 1 ranked player in the @wta. She held the No. 1 spot for a total of 260 weeks.”

King also shared photographs from the 1989 Billie Jean King Cup, featuring former World No. 1 Steffi Graf and the U.S. team’s title-winning campaign. She captioned the post:

“The BJK Cup Vault: 1989 Edition 📸 🏆 USA win the BJK Cup 🥈 Spain finish runners-up 👑 World #1: Steffi Graf📍 Tokyo, Japan.”

Evert responded to the posts with two heartfelt comments. Reflecting on the memories from the 1989 competition, she wrote:

“Sweet, sweet sweet memories, those were the good old days, so much fun,so many smiles, such close friendships….”

She also thanked King for celebrating her historic achievement, adding:

“Why thank you, BJK, and thank you for being my SHERO all these years❤️”

Chris Evert stepped down from the WTA World No. 1 ranking on April 26, 1976, when Evonne Goolagong temporarily took the top spot for two weeks. Evert then regained the No. 1 ranking on May 10, 1976.

When Chris Evert made her feelings known about looking up to Billie Jean King

Chris Evert had spoken about King’s influence on women’s tennis during a 2013 interview for the PBS documentary series “American Masters: Billie Jean King.” Discussing King’s contribution to the sport and the opportunities she helped create for future generations, Evert said:

“That’s an understatement. Did I look up to Billie Jean King? Yeah, I think that every current women’s tennis player goes up to shake her hand and say thank you for putting money in my pocket. Every generation after her should do that, because she put money in our pocket and she raised the sport to be the most high-profile women’s sport in the world, and it still is,” Evert said.

She added:

“How lucky are we to have had Billie Jean King in tennis? She could have been in golf, she could have been in ice skating, she could have been in gymnastics, but to have her in our sport, it propelled our sport to No. 1, as far as the women were concerned.”

Chris Evert retired from professional tennis in 1989. She finished her career with 157 singles titles, including 18 Grand Slam championships. Her major titles comprised seven French Open crowns, six U.S. Open titles, three Wimbledon championships and two Australian Open victories.