WTA Finals: Ashleigh Barty blows cold but ends historic year on top of the world

The 2018 US Open champion is the first female Australian to end a season at the top of the world rankings

Ashleigh Barty reacts during her defeat to Kiki Bertens (AP)

Ashleigh Barty was confirmed on Tuesday as the first female Australian ever to top the year-end world singles rankings, but you would hardly have guessed that fact given her erratic performance here in her second round-robin match at the Shiseido WTA Finals.

Naomi Osaka’s withdrawal from the season-ending tournament because of a shoulder problem midway through the afternoon had ensured that Barty could not be overtaken at the top of the world order until next year. However, in the first of the evening’s two Red Group matches Barty was beaten 3-6, 6-3, 6-4 by Kiki Bertens, an alternate brought in to replace Osaka.

With Belinda Bencic beating Petra Kvitova 6-3, 1-6, 6-4, the results left all four players in the group with a chance of qualifying for this weekend’s semi-finals. In Thursday’s concluding group matches Barty will take on Kvitova and Bencic will face Bertens.

While Barty is focusing only on this tournament, the French Open champion already knows that she will make Australian history this year. The only previous Australian women's world singles No 1 was Evonne Goolagong, who topped the charts for two weeks in the summer of 1976.

After her defeat Barty insisted that she was not thinking about the rankings and instead regretted the fact that she had failed to drive home her advantage against Bertens, who had barely had time to prepare for the match. Two days earlier the Dutchwoman had been in nearby Zhuhai, where she was beaten by Aryna Sabalenka in the final of the Elite Trophy.

In a match that featured 13 breaks of serve, Barty led 3-2 with a break in the second set, only for Bertens to fight back and level the match. In the decider Barty recovered from 0-4 down to 3-4, only for Bertens to hold her nerve and close out her victory. Barty had won all five of her previous meetings with Bertens.

“At the beginning I was struggling a little bit,” Bertens said afterwards. “Of course, I hit this morning on the court, but it's really different from last week, as are the balls. I think as the match went on I felt better and better. My movement was getting a bit better. I was starting to feel the court. I could play a little bit more aggressively and come to the net.I think I played pretty well in the end.”

Although Bertens will have played one match fewer than the other three players in the group, she will qualify for the last four if she beats Bencic in her second match. Bertens would be the first alternate in the tournament’s history to reach the semi-finals.

Kiki Bertens celebrates defeating Ashleigh Barty (Getty)

Bencic recovered from a poor second set to record only her second victory over Kvitova in her six meetings with the Czech. The 22-year-old Swiss, who is making her debut in the year-end finals, made a decisive break of serve at 4-4 in the third set with a scorching backhand return winner before serving out for victory.

Osaka first injured her shoulder in the China Open final in Beijing earlier this month and felt it again during her victory over Kvitova in her opening match here on Sunday. Even after a day’s rest she felt unable to go ahead with her second match.

“It doesn't feel like it's anything more serious than muscular,” Osaka said in announcing her withdrawal. “I think if it was bone-related then I wouldn't be able to lift it, but I am able to do that. It's just a little bit painful. I definitely don't think it's something that I would immediately need surgery for.”

Naomi Osaka has withdrawn from the tournament due to injury (Getty) (Getty Images)

She added: “It kind of sucks because I thought I was playing well. I definitely wanted to win here.”

Osaka also suffered an injury in this tournament last year, when she retired hurt with a leg problem in her third round-robin match, having lost the previous two.

The latest injury completes a roller-coaster year for the 22-year-old Japanese, who began 2019 by winning the Australian Open and going to the top of the world rankings. She often struggled over the next eight months – during which time she parted company with two coaches – before winning two titles in a row in China and Japan before arriving here.

“I wish I was more consistent throughout the year,” Osaka said as she looked back on her season. “Surprisingly, I think this year is better than last year, even though I cried way more this year than I did last year. I also think that's a lesson that I learned.”