Billie Jean King and Serena Williams laugh as Maria Sharapova speaks during the WTA 40 Love Celebration. (Julian Finney/GETTY IMAGES)

Women’s tennis locker rooms on the pro tour aren’t warm, nurturing places. In an individual sport like tennis, top athletes and those aspiring to be see little gain in befriending their rivals.

But earlier this week, when four decades of champions who have occupied the No. 1 ranking gathered at Wimbledon to celebrate the 40th anniversary of the Women’s Tennis Association, the admiration that was difficult to express at the height of their careers came tumbling out.

There was no shortage of egos at the gala, to be sure. Introduced one by one, they included Margaret Court, Evonne Goolagong Cawley, Chris Evert, Martina Navratilova, Monica Seles, Martina Hingis, Maria Sharapova and current No. 1 Serena Williams, to name a few.

But they and the invited audience honored only one with a standing ovation: Billie Jean King, the visionary, architect and driving force behind the players’ union that revolutionized women’s tennis.

As an amateur, King received a gift certificate worth 30 pounds (roughly $45) upon winning her first Wimbledon singles title in 1966. Even after the advent of the so-called Open Era, when players were permitted to accept prize money, King’s reward for subsequent Wimbledon championships was never more than a fraction of her male counterpart.

The WTA’s campaign for equal prize money at all four of the sport’s Grand Slams wasn’t realized until 2007. This Wimbledon’s 2013 women’s champion will collect 1.6 million pounds (roughly $2.4 million) — same as the men’s.

But in 1973, when women were routinely denied the opportunity to have credit cards in their name, King’s vision in creating the WTA was to make women’s tennis a viable career — one that guaranteed a place to compete, respect as professional athletes, a decent income and adequate financial security in retirement.

At the WTA gala, the beneficiaries of her efforts were arrayed on stage around her, including Evert, who in 1976 became the first female athlete to surpass $1 million in career earnings; Navratilova, the first female athlete to earn $1 million in a single season; and Sharapova and Williams, whose career prize money tops $23 million and $41 million, respectively.

Along with China’s Li Na, the world’s No. 6 tennis player, Sharapova and Williams are the only women on Forbes’ 2013 list of the most handsomely compensated athletes in the world.

King and Betty Stove, who was chosen to be the WTA’s first treasurer because she was tall, imposing and good with money, told stories about the union’s early years.

Stove recalled having few friends on the tour at the time. She had even fewer, she said, once she tried collecting the $250 annual dues from rivals in the locker room.

From there, the memories and confessions spilled out of one player after another.

Tracy Austin recalled her joy over getting to be a ball-girl for a match between Evert and Navratilova once.

Seles said she had a poster of Navratilova in her room as a little girl.

The thrice-divorced Evert confessed about Navratilova, her near career-long rival: “She’s my longest relationship! And we’re still friends.”

For so many years, when they occupied the No. 1 and 2 rankings in the sport, Evert and Navratilova were the only players left in the locker room once tournaments got down to the finals. Regardless who won, it seemed, one would end up comforting the other.

But the best moment, Navratilova recalled, was when they teamed up to play doubles together at Wimbledon in 1976 and won.

“That was the only time we were happy at the same time,” Navratilova said, laughing.

Williams closed the proceedings with an eloquent speech about the WTA’s significance. But before that, she paid personal tribute to Seles, saying: “I started grunting because of you!”