Ashleigh Barty progressed to the semi-finals of the WTA Finals in Shenzhen with a convincing victory over Petra Kvitova.

The Australian’s 6-4 6-2 win means she reaches the last four as Red Group winner in her debut appearance at the WTA Finals, while Kvitova leaves having lost all three of her matches.

The pair had met four times previously this year, sharing two wins apiece, and the start of the match followed that close nature of their recent rivalry.

Kvitova saved two break points early on but could not prevent Barty from breaking in her next service game.

The world number one then had to save break points on her own serve in back-to-back service games, but her overall consistency told as she closed out the first set. 

Kvitova’s 20 unforced errors really hurt as her trend of being too aggressive continued.

The Czech continued to squander good positions at the start of the second set and was broken twice in a row, creating a deficit she could not recover from. 

Barty grew in confidence with every point and closed out the win easily.

Belinda Bencic is also through to the semi-finals in her first appearance at the season-ending showpiece after Kiki Bertens retired due to a viral illness.

Bertens, who was a replacement for the injured Naomi Osaka and shocked Barty in her previous match, broke early and held a 5-3 lead in the first set.

But as Bencic broke back, Bertens called for her coach, telling her she had trouble hitting backhands.

Bencic closed out the first set 7-5 and after calling both the trainer and the doctor Bertens made the decision to retire.

The semi-finals will take place on Saturday and there is one spot remaining, after defending champion Elina Svitolina qualified yesterday from the Purple Group.

That final spot will be taken by either Simona Halep or Karolina Pliskova, who play each other tomorrow.