After a glittering 27-year professional career in which she became one of the greatest players of all time, Serena Williams is preparing to bid farewell to tennis at the major where it all began.

The 40-year-old sporting icon ended the guessing game surrounding her future earlier this month by revealing that the "countdown" to her retirement had started, with her final Grand Slam appearance expected at the US Open in New York starting on Monday.

"There comes a time in life when we have to decide to move in a different direction," Williams wrote. "That time is always hard when you love something so much."

The announcement sets the stage for what will be an emotional farewell for Williams, who faces unheralded world number 80 Danka Kovinic in Monday's first round at the Arthur Ashe Stadium.

Williams won the first of her 23 Grand Slam singles titles as a 17-year-old at the 1999 US Open, beating Martina Hingis in the final.

That breakthrough victory confirmed what had become apparent ever since her professional debut four years earlier: that Williams, alongside sister Venus, was a rising force in women's tennis.

While 1999 marked her first singles Slam, by then Williams had already won mixed doubles titles at Wimbledon and the US Open in 1998.

Her win in the 1999 singles final would light the touchpaper for the most dominant career of any female player in the Open era, her 23 Grand Slam titles second only to Margaret Court's 24.

While a record-equalling 24th Grand Slam singles title is likely to remain beyond her next week, Williams has nevertheless produced a collection of records that in all probability will never be broken.

With Williams not expected to mount a sustained challenge, all eyes will be on Poland's world number one Iga Swiatek in the women's draw.

The 21-year-old was the form player in women's tennis earlier this year, reeling off victories at the Qatar Open, Indian Wells and Miami Open before claiming wins on clay in Stuttgart and Rome en route to her second Slam singles title at the French Open.

However, Swiatek has struggled to recapture that dominance during the North American hardcourt season, making early exits at both the Cincinnati Masters and Canadian Open.