One of the greatest female athletes of all time, Billie Jean King, turned 80 on Wednesday.
The 12-time Grand Slam singles champion celebrated the milestone birthday by playing tennis and eating cake baked by her niece before thanking her supporters.
'Today, I am 80 years young,' King said on X. 'Relationships are everything. I am fortunate to have been surrounded by loved ones all my life.
'I look forward to each day. Having Ilana [her wife] by my side is my best gift,' King continued. 'Creating opportunities for others makes me so happy. And I'm not done yet!'
The video King posted on X of herself playing tennis shows her returning the ball with forehands and backhands that are reminiscent of her athletic prime.
Billie Jean King stands from her seat at a court inside the tennis grounds named in her honor
King can still return the ball at 80, more than 30 years after she officially retired from tennis
King celebrated the birthday with her niece (pictured) and with eight candles on her cake
King has already proved she has no intention of slowing down when she competed on FOX's 'The Masked Singer' earlier this fall.
She was under the 'Royal Hen' costume and sang 'Philadelphia Freedom' by Elton John, which was ironically written about King.
King may also be best known for winning the 'Battle of the Sexes' match against Bobby Riggs 6-4, 6-3, 6-3 in 1973.
King won a total Grand Slam titles, including 12 singles, 16 women's doubles and 11 mixed doubles.
20 of the tennis legend's Grand Slam titles came at Wimbledon, tennis' most hallowed ground.
But it New York City that pays tribute to the all-time great, with the US Tennis Center in Flushing Meadows dedicated to her.
Michelle Obama hugs King during the opening night ceremony of the 2023 US Open
The US Open celebrated King in Queens in August, with this year's tournament marking the 50th anniversary of the Grand Slam becoming the first to offer equal prize money to men and women - something which King was a pioneer for.
Former First Lady Michelle Obama was part of the ceremony at Arthur Ashe, introducing the 79-year-old tennis legend by recalling how King, the US Open champion in 1972, rallied her fellow women players to successfully threaten a boycott of the next year's tournament unless women got the same pay as men.
King promised never to stop fighting to maintain that hard-won progress to cheers from the star-studded crowd.
In 2009, King became the first female athlete to be given the Presidential Medal of Freedom.