The American, who will turn 41 this month, bid an emotional goodbye to the US Open with a third-round loss to Australian Ajla Tomljanovic on Friday, in what may have been the last singles match of her glittering career.
Although Williams left the door slightly open on an unlikely comeback, her apparent departure - not unexpected, given Williams' struggles with form and injury in the past 12 months - would have sent shivers down the spines of tennis administrators and organisers.
"She's box office," former British number one Greg Rusedski summed it up on Sky Sports after Williams informed the world of her decision last month in a Vogue article.
"She's carried women's tennis for the last two decades with her sister Venus as well. You've obviously had other great players around them, but she brings your non-tennis fan to the sport.
"If you know absolutely nothing about tennis, you know the name Serena Williams. She's iconic and we're losing an icon of our sport and she will be truly, truly missed."
But it will not just be a loss for women's tennis. Williams could be the first in a series of ageing greats to call time on their playing careers in the near future.
Like Williams, the triumvirate of Roger Federer (41), Rafa Nadal (36) and Novak Djokovic (35) have dominated tennis for the last two decades and revolutionised the sport, drawing in new and old fans and a long line of sponsors.
All of them continue to lure fans to the stands, mobile and television screens even after two decades on the tour, while their commercial pull still mesmerizes brands and advertisers.
Injuries to Williams, Federer and Nadal in recent years have raised the question of their retirement time and again. Fans and pundits have wondered how the sport would cope with the prospect of losing its most marketable athletes.
Federer has had multiple knee surgeries in the last two years and has not played a competitive match since going down in the quarter-finals of last year's Wimbledon.
The 20-time major winner has only committed to playing the Laver Cup this month and his hometown tournament in Basel in October. It remains unclear if the father of four would be ready to commit to the rigours of the tour again.
Nadal is a bit younger, but a chronic foot issue forced the Spaniard to contemplate retirement in 2021 and again this year after he won a men's record 22nd major title at the French Open, playing with numbing injections before each match in Paris.
A radio frequency treatment eased the pain in his foot and allowed him to play Wimbledon, but the left-hander does not know whether the injury will flare up again.
Djokovic is the youngest among the lot, undoubtedly the fittest and appears to be the best bet to keep the flag flying for tennis' older generation.
The Serbian won his 21st major title at Wimbledon last month and has made it clear he does not lack motivation in chasing more silverware.
While the so-called Big Three of the men's game have continued to stave off the younger generation when it comes to major success, Williams' tennis career has been less productive in the past couple of years.
Her last Grand Slam triumph came in 2017 and she did not win a WTA title since lifting the ASB Classic in Auckland at the start of the 2020 season.
Despite all that, Williams remained the biggest draw in women's tennis whenever she took the court.
"She's an inspiration for a lot of people around the world. She gave a lot to tennis, so we are lucky to have had such a great ambassador like Serena for such a long time," Nadal said after Williams's defeat on September 2nd.
"She deserves to choose whatever fits for her at this stage of her life."
