Ashleigh Barty has sealed her place in the semi-finals of the elite season-ending championships and eliminated Petra Kvitova with a decisive 6-4 6-2 win over the dual Wimbledon champion.

Rebounding from her last-up pool loss to Kiki Bertens, Barty delivered the most impressive serving display of the WTA Finals thus far to top the Red Group in Shenzhen with a 2-1 record for the week.

The first eight matches of the tournament had produced an extraordinary 65 service breaks – at an average of one every three games – on the notoriously slow purple indoor court.

But, clutch under pressure, Barty was unbroken on Thursday night, winning 79 of points after landing her first delivery and firing down six aces.

And she needed to be, with Kvitova playing typically aggressive tennis in her desperate attempt to remain in the semi-finals hunt.

Attacking at every opportunity, the Czech pounced on anything remotely short, especially second serves, winning 61 per cent of rallies after Barty faulted.

Barty stayed cool, breaking Kvitova in the fifth game of the opening set and twice more in the second, which was enough to give Australia’s top seed her third straight win over the world No.6.

“I felt like I executed really well tonight,” Barty said.

“I knew I had to play aggressively and it was important when I was serving to keep my nose in front.

“It’s really exciting to have another chance to play again here on this beautiful court.”

Barty had lost to Kvitova in the pair’s first four encounters, including in straight sets in this year’s Australian Open quarter-finals.

But Barty is different player nine months on, a grand slam champion with the year-end world No.1 ranking all wrapped up after a stellar 2019 campaign that has already yielded three titles from five finals and an eye-watering $11.44 million.

The unprecedented windfall for an Australian player in a single season has more than doubled her entire career earnings.

And there could be much more to come after Barty became the first Australian since Samantha Stosur in 2012 to qualify for the semi-finals at the season finale.

Barty is guaranteed at least $1.45 million for the week if she makes the last four in Shenzhen – and could land a $5.98 million pot of gold with victory in Sunday’s final.

Thanks for coming.

The 23-year-old won’t learn who she plays on Saturday until after Friday night’s final two round-robin matches from the Purple Group.

Her possible opponents are defending champion Elina Svitolina, Wimbledon winner Simona Halep or world No.2 Karolina Pliskova.

Bencic plays Bertens in Thursday night’s second match to determine the other semi-finalist from Barty’s group.