Even Billie Jean King wanted to capture the moment.

"Her incredible career made its mark on tennis history. And yet her greatest contributions may be yet to come," said King, the former world number one and co-creator of the Women's Tennis Association, on Twitter.

"Thank you, Serena. Your journey continues."

Williams' third-round defeat by Tomljanovic - an extraordinary three hours befitting of the 40-year-old's final bow - brings down the curtain on a 27-year professional career that yielded 23 major singles wins.

She has been an inspiration to many since she won her first Grand Slam singles title at the 1999 US Open, beating then-world number one Martina Hingis to become the second African-American woman, after Althea Gibson in 1958, to win a major singles tournament.

Back then, fellow American Coco Gauff was still six years from being born but Williams soon became an idol for the now 18-year-old, who is into the US Open fourth round for the first time.

"It is because of you I believe in this dream. The impact you've had on me goes beyond any words that can be put together and for that I say thank you, thank you, thank you, GOAT!"

The farewell began at the beginning of the week when A-listers and Serena's friends and family packed the Arthur Ashe Stadium for her first-round match, ready to witness her final bow.

And they returned for two more singles matches - as well as one doubles where she teamed up alongside sister Venus - as Williams showed her incredible fighting spirit to reach the third round and even had fans contemplating the possibility of an unlikely fairytale run to one last title.

Those watching her - and the video montages celebrating her before each match - in the stadium this week included some of the greats of the fashion, sports and Hollywood worlds, demonstrating how the American has transcended tennis in so many ways.

The tributes flooded in from far beyond the tennis sphere, with former United States First Lady Michelle Obama saying: "How lucky were we to be able to watch a young girl from Compton grow up to become one of the greatest athletes of all time.

"I'm proud of you, my friend - and I can't wait to see the lives you continue to transform with your talents."

Among colleagues on the WTA Tour paying tribute were Ons Jabeur and Caroline Garcia, with the latter describing her as "such a legend", while on the men's side, 22-time Grand Slam winner Rafael Nadal said Williams was an "amazing champion".

Elsewhere from the world of sport, swimming great Michael Phelps praised Williams' tenacity and drive.

"Her tennis accomplishments speak for themselves, but one of the things I admire about her is she simply doesn't quit," the 23-time Olympic champion said.

"On or off the court her will, her strength, her determination... she simply never gives up. She's a great example to us all."

Golfer Tiger Woods, who was in Williams' player box for her second-round win over Anett Kontaveit, said: "You're literally the greatest on and off the court. Thank you for inspiring all of us to pursue our dreams."

NBA great Magic Johnson said: "Serena has meant so much to sports, the game of tennis, the world, every little girl, and even more to every little black girl across the globe.

"Serena proves that you can dream bigger than where you come from. From South Central Los Angeles, to the greatest the world has ever seen… what a story!"

Fans flock to New York to celebrate the 'GOAT' and the 'Legend'

Before all of Williams' matches this week, there was a huge buzz outside of Ashe with many fans wearing Serena T-shirts and saying they had bought tickets following the announcement of her impending retirement last month.

As Gauff alluded to, Williams has been a huge inspiration to African-American women and that was a common theme when fans were asked about their love for the player.

Many people came to New York from across the United States to see her final tournament - including Jennifer Chenier and Renicha Jones who have flown over from Houston, Texas.

"Serena is the greatest of all time and I've always loved her. But this is my first time watching her!" Jennifer, whose T-shirt said 'Serena. The Woman. The Myth. The Legend', told BBC Sport.

"Growing up in Compton and what she's achieved through her being African-American and everyone hating on her and talking about other things besides just her skill is incredible.

"I don't play tennis, the only reason I watch is because of Serena and Venus, seeing them do their thing."

Arlene and Princess Kinch, a mother and daughter from New Jersey, said it would feel strange to see tennis without such an icon.

"I've never know life without Serena," said 20-year-old Princess. "She's just phenomenal.

"She always says the right things. She knows her worth, knows how great a player she is and does not take mess from anyone who tries to downplay her success."

Arlene added: "She has been awesome for the game and for the cause, she's always doing what is right.

"I'm inspired by the Williams sisters - where they came from, how they got to where they are and what they've achieved. We're all going to miss them."