Australian Ajla Tomljanović defeats Serena Williams at US Open

Australian Ajla Tomljanović has defeated Serena Williams in the champion's final match of her tennis career. Turning 41 in three weeks, Williams announced last month she was "evolving away from tennis" after more than 20 years at the top.

The epic encounter between Serena Williams (left) and Ajla Tomljanović (right) lasted three hours and five minutes. Source: AAP / Sakchai Lalit/AP

Ajla Tomljanovic has ended Serena Williams' storied career with a famous third-round US Open triumph over the retiring legend in New York.

Tomljanovic defied the sellout, partisan crowd in Arthur Ashe Stadium with a stirring, nerve-jangling 7-5 6-7 (4-7) 6-1 third-round victory over the 23-times grand slam champion on Friday night.

The epic encounter lasted three hours and five minutes with Tomljanovic finally prevailing on her sixth match point.

The last titanic game stretched more than 15 minutes alone.

Serena Williams remains the holder of the most grand slam singles titles in the 54-year era of professional tennis, having eclipsed Steffi Graf's 22. Source: AAP / John Minchillo

For all Williams' fighting spirit, Tomljanovic could not to be denied with the two-time Wimbledon quarter-finalist advancing to the fourth round at Flushing Meadows for the first time after her illustrious opponent netted a forehand into the net.

Turning 41 in three weeks, Williams announced last month she was "evolving away from tennis" after more than two decades dominating the women's game.

The American will walk away one major title short of Margaret Court's all-time record 24 grand slam singles crowns.

Williams, though, remains the holder of the most grand slam singles titles in the 54-year era of professional tennis, having eclipsed Steffi Graf's 22.

All up, she won six US Open titles, Wimbledon and the Australian Open seven times each and the French Open on three occasions.

Alas, her last slam came while three months pregnant with daughter Olympia at the 2017 Australian Open when Williams beat older sister Venus in the final.

Williams subsequently lost four more grand slam deciders in her obsessive pursuit of Court's record, all four in straight sets - at Wimbledon and the US Open in both 2018 and 2019.

Earlier on Friday, Tunisian fifth seed Ons Jabeur survived a thrilling duel to down home hope Shelby Rogers 4-6 6-4 6-3 to also make the fourth round at Flushing Meadows for the first time.

Ajla Tomljanović returns a shot to Serena Williams during the third round of the US Open. Source: AAP / Charles Krupa

The Wimbledon finalist squandered six of the eight break points she earned in the opening set but hit her stride in the second as she dropped just two first- serve points on Friday.

Rogers called on the trainer to receive some treatment on her right arm before the start of the third set. With Jabeur sprinting through the first four games it seemed all over.

But the American refused to cave in and fought off five match points from 0-40 down in the seventh game to hold serve, before handing Jabeur victory on her sixth match point.

"Crazy match," Jabeur said.

"Even down 5-1, 40-love she doesn't make the mission easy for me ... I'm very happy that I kept fighting and went until the end."

Coco Gauff rolled through her match against fellow American Madison Keys, winning 6-2 6-3 to reach the last 16.

The 18-year-old advanced to face China's Zhang Shuai.