Shenzhen, China, 3 November 2019 | Darren Walton (AAP)

Ash Barty is one tantalising win away from banking the biggest cheque in tennis history after scrapping her way into the final of the prestigious season-ending championships in Shenzhen.

Barty doggedly staved off 11 break points in a gritty 4-6 6-2 6-3 victory over world No.2 Karolina Pliskova to book a title decider on Sunday night against defending champion Elina Svitolina.

Svitolina was leading Belinda Bencic 5-7 6-3 4-1 in Saturday night’s first semifinal when the Swiss retired in tears.

After receiving a medical time-out in the opening set for treatment for a hamstring injury, Bencic spent much of the remainder of the match sobbing through the pain before eventually calling it quits.

Barty spent much of her match under the pump. But, as she has done so often this year, the world No.1 raised her game when it mattered to pull out a tour-best 13th comeback win of the season from a set down.

“I felt like that whole match was an incredibly high level. I didn’t do much wrong in the first set and I’m just really pleased to get another chance to play out here,” Barty said.

The 23-year-old is the first Australian woman to make the final of the season-ending showpiece since her idol Evonne Goolagong Cawley lost to Martina Navratilova in 1978.

“It’s been an incredible year for myself and my team. It’s the perfect way to cap it off,” Barty said.

“An opportunity in another final in such a prestigious event, knowing you’ve played the best of the best during the week, now you have the opportunity to play for a title, it’s really special.”

If she wins, Barty will be Australia’s first champion since Goolagong Cawley, who captured the trophy twice, in 1974 and 1976.

The French Open champion would also pocket $US4.42 million ($A6.4 million) in prize money.

Barty, though, will need to reverse a run of five losses from five previous meetings with Svitolina, whose victory over Bencic was also the Ukrainian’s 10th consecutive win at the WTA Finals stretching back to 2017.

Svitolina marched to the title last year in Singapore without dropping a match and is threatening to repeat the feat in China.

“It’s always an extremely tough match against Elina. She’s an incredible opponent, knows how to win on the biggest stage,” Barty said ahead of her sixth final of a phenomenal season.

“I have an opportunity to try something because previously what we’ve done hasn’t quite worked or I haven’t executed well enough over a long enough period to be effective.

“It’s an opportunity to come out, try to enjoy it, try to finish off the season really well, a season that’s been magical.”

Should Svitolina lift the trophy unbeaten, she’d collect $US4.725 million ($A6.84 million).

Regardless of whether it’s Barty or Svitolina who prevails, no two women or two men have ever squared off for such riches in more than 50 years of professional tennis.

“The biggest thing, it’s been a growth of women’s sport. For me individually, and I think for all of us players individually, it’s not something we think about,” Barty said of the extraordinary prize money.

“It’s more of kind of a general progression of putting our sport more on the map.

“We have the most beautiful sport, it’s a global sport. Now we’re getting more attention. I feel like we’ve earned that.”