NEW YORK, Sept 12 ― As a weary Serena Williams packed her bags and left Flushing Meadows in the early hours of yesterday morning, her latest bid for a record-equalling 24th Grand Slam title snuffed out in the semi-finals of the US Open, one question was left hanging in the balmy night air: if not now, when?

For nearly four years, Williams has been trading groundstrokes with Father Time as she attempts to add one more Grand Slam title to her collection, cementing her claim to be the greatest women's tennis player ever seen.

Yet since her 23rd and last major title at the 2017 Australian Open, when she was pregnant with daughter Olympia, the window of opportunity has been closing.

Did that window slam shut on Thursday night? Only time will tell.

Certainly, throughout her career, be it returning from serious illness to dominate her sport, or from continuing to compete at the highest level at an age when most of her contemporaries have long since retired, Williams has repeatedly demonstrated that writing her off is a mug's game.

Opportunity lost?

But it is hard to avoid the conclusion that the 2020 US Open offered Williams by far her best chance of finally matching Margaret Court's total of 24 Grand Slam singles crowns.

Williams, who will turn 39 this month, seemed disinterested by the question of whether she will ever reach that milestone.

"How does making it deep into majors affect your resolve to keep up the pursuit for as long as it might take to get to number 24?” one reporter asked her following Thursday's gruelling 1-6, 6-3, 6-3 defeat to Victoria Azarenka.

"I don't know,” she replied. "I just ― I don't know. I haven't thought about that actually. I don't know.”

For many, however, there was an unmistakeable sense of an opportunity gone begging.

The unique circumstances of this year's US Open, taking place in a season upended by the coronavirus pandemic, had offered Williams a path to the title far less hazardous than it might normally have been.

Six of the top 10 players in the world, including world number one Ashleigh Barty and world number two Simona Halep, opted to skip the tournament.

So too did the defending champion, Canada's Bianca Andreescu, who defeated Williams in the 2019 final.

'Weakest US Open'

It meant three of the four reigning Grand Slam champions were absent from New York. Tracy Austin, the two-time US Open champion, called it the "weakest US Open of the Open era.”

And by the time Thursday's semi-finals had rolled around, Williams was the highest remaining seed in the draw, after top seed Karolina Pliskova exited in the second round and second seed Sofia Kenin bowed out in the last 16.

Throughout the past fortnight, Williams had offered plenty of reminders that she still possesses a substantial residue of the talent that has put her at or near the pinnacle of women's tennis in four different decades.

In her quarter-final against Tsvetana Pironkova, she hammered down no fewer than 20 aces and an array of serves that were borderline unplayable.

However the resurgent Azarenka, who like Williams has successfully continued her career after becoming a mother, proved a bridge too far in the last four.

It means Williams will now turn her attention to the rescheduled French Open in Paris later this month.

While she has won at Roland Garros three times before, clay is by no means her preferred surface.

Her last victory in Paris came in 2015; in 2019 she was eliminated in the third round. By any objective measure, the 24th title will probably have to wait.

In any case, some wonder whether too much is made of the "quest for 24”.

US tennis legend Billie Jean-King points out that in other eras, many top players regularly chose to skip certain Grand Slams altogether in their prime.

"You gotta remember we didn't play the Australian Open for many, many years - we played the Virginia Slims in San Francisco,” King said in a recent interview.

"And we also played Team Tennis during the French Open. "I think (Chris Evert and Martina Navratilova] would have had a lot more than 24, quite frankly.” ― AFP