Serena Williams has pushed the boundaries of what women can achieve in the male-dominated world of sports. The all-time women's leader in Grand Slams won with 23, Williams' legacy is more than secure. But Williams, age 40, is not done yet, despite announcing her plans to retire following this year's US Open. After a dominant first-round victory against Montenegrin Danka Kovinić, Williams received all the praise she can get. And who else is better to get it from than Billie Jean King, one of the female pioneers and icons of Tennis.

“You are fearless. I love it. And you hate to lose. And it is great,” the 78-year old King quipped, eliciting laughters from the crowd as an emotional Williams looks on, via ESPN. “You've touched our hearts and minds, [told us] to be our authentic selves, to use our voices, to dream big.”

Williams is a known champion of the Black community, fighting for social justice and empowering other African-Americans to stand up for their rights as well. She and her sister Venus Williams has had considerable influence on encouraging black athletes to pursue their dreams as well. And King recognizes that Williams' impact goes way beyond her tennis prowess.

“Thank you for your leadership and commitment to diversity, equity, and inclusion,” King, who wore pink as a tribute to Williams' favorite color, added. “Especially for women, and for women of color.”

King has long been a fan of Williams; the tennis legend spotted Williams when she was just six years of age. King knew from the moment she saw Williams' serve that she had ‘it'.

“Her serve is the most beautiful in the game,” King expressed.

Serena Williams will face Anett Kontaveit of Estonia, the No. 2 player in the world, next which could be the swansong of her trophy-laden career.