Ashleigh Barty's ambitions and desires have been well and truly sated. Her time at the top was too short for tennis, but not for the person who matters most.

"I [no longer] have the physical drive, the emotional want," the 25 year old has said.

"I just know that I'm absolutely spent."

Perhaps the decision has been accelerated by the Covid-19 pandemic, with its enforced bubble life and the difficulties of returning home to Australia.

Barty spent six months on the road last year and, in 2014 as an 18-year-old, she suffered home sickness and depression before taking a two-year break from the tour.

But surprising though the announcement is, with Barty in her 121st week as world number 1, the Queenslander never seemed likely to be playing into her 30s.

She is never happier than at home near Brisbane, with family and friends - barbecue tongs in one hand and a cold beer in the other.

There are many parallels to the decision taken by Justine Henin in May 2008.

She was also 25, world number one, and had won two Grand Slams in the previous 12 months. The announcement of her retirement, just two weeks before the French Open which the Belgian had won for the previous three years, was a monumental surprise.

But, like Barty, she also said she had given everything and wanted to try her hand at something new.

Henin, though, came back for more. Motivated by Roger Federer completing his set of Grand Slams at Roland Garros in 2009, she wanted to see whether she could win Wimbledon, which would remain the only major title to elude her.

The only Grand Slam singles title missing from Barty's resume is the US Open. Only 10 women in history - and only Margaret Court, Billie Jean King, Chris Evert, Martina Navratilova, Steffi Graf, Serena Williams and Maria Sharapova in the Open Era - have been able to win all four Slams.

Could Barty one day be tempted? It is always possible, of course, but she seems to me to be a less likely candidate for a comeback.

And I do not say that because of the conditions at the US Open, although Barty's long-serving coach Craig Tyzzer made some interesting observations about that at this year's Australian Open.

"The US Open really needs to change the ball for the girls. It's a terrible ball for someone like Ash - the ball itself is so light," he said.

"I had to change her racquet just to get any sort of control of the ball. If they keep that ball the same, no-one like Ash will win that tournament."

When returning to tennis in 2016, after playing professional cricket for Brisbane Heat in the inaugural women's Big Bash League, Barty admitted having missed the competition and the one-on-one battles.

Her fiancée, Garry Kissick, is a trainee golf professional, and given Barty's low single figure handicap, there is sure to be further speculation about her one day embarking on a third professional sport. Once, that is, she has enjoyed "the next phase of life as Ash Barty the person, not Ash Barty the athlete".

It is unusual for players to retire so young when injuries are not a factor. Jennifer Capriati had well-documented off-court issues, but the initial retirements, in their 20s, of Tracy Austin, Martina Hingis and Marion Bartoli were predominantly caused by ailing bodies.

Barty's departure makes you even more grateful for the longevity of the Williams sisters - and concerned for the short term future of the WTA Tour.

The 2020 French Open champion Iga Swiatek is likely to take over as world number 1 after the Miami Open - but only if Barty asks for her name to be removed from the rankings. Maria Sakkari, Barbora Krejcikova and Aryna Sabalenka are the other current members of the top five - and their achievements are not yet widely celebrated outside the sport.

Naomi Osaka is also playing sparingly, but there are plenty of reasons for long-term optimism in the shape of teenagers Emma Raducanu, Coco Gauff and Leylah Fernandez.

To lose a player like Barty, who has won 25 of her last 26 matches on the tour and been world number 1 for the past 114 weeks, leaves a gaping hole though.

She has become the reference point for women's tennis, having carried herself with class and provided inspiration for indigenous communities.

And Barty has charmed us with the grace of her truly beautiful game.