Although almost every day of the WTA finals has provided another nightmarish reminder of just how gruelling the season is – and how much everyone could do with a holiday – the Shenzhen crowd will get the showdown it deserves as the world No 1, Ashleigh Barty, and the defending champion, Elina Svitolina, face off for the biggest prize money in tennis history.

It was sealed by two contrasting results on Saturday. Belinda Bencic became the tournament’s fourth casualty in five days when she retired with a leg injury sustained in the first set of her 7-5, 6-4, 4-1 loss to Svitolina, then Ashleigh Barty confidently recovered to beat Karolina Pliskova 4-6, 6-2, 6-3.

It was a bitter missed opportunity for Bencic. After her prodigious youth was derailed with surgery and countless injuries, this has been the year she finally blossomed. Her struggles have forged a more mature player and she has used that maturity to return to the top 10 and reaching her first grand slam semi-final at the US Open with a win over the defending champion, Naomi Osaka.

Bencic started the match with discipline and focus, taking the ball early and intelligently opening up the court. She took the first set, but she had arrived in Shenzhen after a manic race to seal the final spot and her efforts finally caught up with her.

As Bencic’s foot began to cramp, Svitolina took full advantage, breaking in the opening game of the second set and never looking back. The Ukrainian was vicious, serving 16 aces and lengthening the rallies until the pain was too much and Bencic, eventually, had to tap out.

The great irony of Svitolina soaring while so many of her rivals’ bodies have collapsed is that much of her own season has been marred by injury. The struggles with her knees have been so significant that she arrived at Wimbledon with an ugly seven losses in eight matches. Her best form seemed a long way away.

Svitolina rescued her year on the stage she had previously struggled badly on, reaching her first grand slam semi-final at Wimbledon and an excellent US Open, but at times it has still been a struggle. Svitolina won an astonishing nine titles in 2017 and 2018, yet until had failed to reach a final this year. She has found her killer instinct again in Shenzhen.

Belinda Bencic receives treatment for the injury that eventually cost her the match. Photograph: Aly Song/Reuters

Facing her from across the net will be the best player of the year. The last time Barty faced Pliskova, she produced the serving performance of her life, slamming down 15 aces to win the Miami title in March. That marked by far the biggest title of her career at that point and it propelled her into the top 10, imbuing her with the confidence to do so much more.

Although Barty has not blown the world away since her surprise Roland Garros title, her consistent results have reflected how steady her game is and how many options she has at her disposal. Many players struggle after their first title, but even without producing her best tennis she has continued to go deep into big events.

Pliskova played some breathtaking tennis to overcome Simona Halep on Friday and she started well against Barty, but Barty has an entire toolkit reserved for making it so much tougher to tee off and laser winners on to the lines.

Barty’s backhand handcuffed Pliskova and forced her to constantly bend her knees throughout, and her whippy topspin forehand spun high out of the Czech’s strike zone. She could only maintain her level for one set before Barty’s resourcefulness overwhelmed her.

Barty turned the match around with the hard-earned confidence of a player who is now 55-11 in 2019 and the certain WTA player of the year. Her season has been a dream and her final WTA match of the year will require some of the best tennis she can play: Svitolina is now on a 10-match winning streak at the WTA finals and she is yet to lose to the Australian in five meetings.