Svitolina into title decider at WTA Finals

Elina Svitilona is a win away from bagging the biggest cheque in tennis history after advancing to her second straight final at the season-ending championships in Shenzhen.

The defending champion was leading Belinda Bencic 5-7 6-3 4-1 on Saturday night when the Swiss retired from their semi-finals in tears.

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

Champion last year in Singapore, eighth-seeded Svitolina has now won 10 consecutive matches at the showpiece event stretching back to her final round-robin match in 2017.

The Ukrainian will play the winner of Saturday night's second semi-final between world No.1 Ashleigh Barty and second seed Karolina Pliskova for the title on Sunday.

Should she lift the trophy unbeaten, Svitolina will claim $US4.725 million ($A6.84 million) in prize money - the biggest-ever winners' purse for a men's or women's tournament.

Svitolina was the only player in the elite eight-woman field to have arrived in Shenzhen yet to win a title in 2019.