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

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

Svitolina was leading Belinda Bencic 5-7 6-3 4-1 in Saturday night’s first semi 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 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.

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

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 $US4,420,000 ($A6.4 million) prize money for the week.

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

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

Should she lift the trophy unbeaten, Svitolina will claim $US4.725 million ($A6.84 million) in prize money.

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.