Tributes have poured in across the sporting world for Serena Williams following her apparent US Open swansong on Friday, though the 23-time grand slam winner has kept the door ajar on a shock return.

The American, widely considered one of the greatest sportspeople of all time, suggested she would step away from top-level tennis following the tournament at Flushing Meadows.

Following a 7-5 6-7 (4-7) 6-1 loss to Australia's Ajla Tomljanovic in the third round, her journey now looks to be over – though the 40-year-old admittted "you never know" when asked about future appearances.

Her likely last dance, however, has prompted an outpouring of glowing tributes from far and wide, with a host of major names paying their respects to an unparalleld career.

15-time major-winning golfer Tiger Woods called her "the greatest on and off the court" while four-time NBA champion LeBron James hailed her as "so dope".

Former US Women's National Team captain Alex Morgan, meanwhile, lauded her impact on women's sports, stating that she fought "until the last point, always", while Olympian Simone Biles thanked her for "transcending sports for black athletes".

Ex-India cricketer Sachin Tendulkar, who like Williams defied age to remain near the top of his sport through to his twilight years, added that "age is not what the body tells you, but what your mind tells the body".

Mercedes' George Russell also offered his congratulations, while fellow WTA players Coco Gauff and Ons Jabeur both weighed in on the icon's final match with warm words of praise.