image credit - Serena William

NEW YORK Serena Williams, playing like a world number one rather than a woman ranked below the top 600,

image credit - Serena William

stunned world number two Anett Kontaveit 7-6(4), 2-6, 6-2 and advanced to the third round of the US Open, putting her retirement intentions on hold.

image credit - Serena William

Defeat has always been difficult for the extremely competitive Williams, and the 40-year-old American's unwavering determination to win was on full show during an engrossing two-hour 27-minute encounter of unexpected high quality, frenetic intensity, and drama.

image credit - Serena William

Williams announced her retirement earlier this month, stating she was "moving away from tennis" but never announcing that the US Open would be her final event.

image credit - Serena William

Williams will return to centre court on Thursday for a doubles match with older sister Venus, followed by a third round encounter against Australian Ajla Tomljanovic, who defeated Russia's Evgeniya Rodina 1-6, 6-2, 7-5.

image credit - Serena William

When asked how she beat the world number two, Williams replied, "I'm a fairly decent player.

image credit - Serena William

"This is what I do best - I love a challenge and rising to it."

image credit - Serena William

"It's really come together in the last two of matches here in New York. I'm quite competitive, so I'm just counting it as a bonus. I don't have anything to prove."

image credit - Serena William

But, following two victories and a secure passage into the third round,

image credit - Serena William

 Williams' once-unthinkable ambition of walking off into retirement with an elusive 24th major that would tie her with Margaret Court at the top of the all-time list may be coming true.