Kiki Bertens produced the shock of the WTA Finals so far as she beat world number one Ashleigh Barty, while Belinda Bencic kept her hopes alive with victory over Petra Kvitova.

Bertens, who came in as a replacement for the injured Naomi Osaka, came back from a set and break down to defeat Barty 3-6 6-3 6-4. 

Meanwhile, Switzerland’s Bencic won 6-3 1-6 6-4 against Kvitova, who has now lost both her matches at the event.

Barty had the chance to seal qualification to the semi-finals, but Bertens, who has now played for seven consecutive weeks, took advantage of being called up to the event last-minute to defeat the Australian for the first time in six meetings.

Despite exchanging breaks twice with Bertens in the opening part of the match, Barty looked the more patient player as she closed out the first set with a love hold.

The Dutch World No 10 saved two break points in the first game of the second set, but could do nothing in her next two service games as Barty’s consistency looked to be taking her safely through to the semi-finals.

But as was the case in the first set, Bertens showed great resolve to break straight back and stay in contention, and thanks to her more aggressive play - as her 12 winners in the second set showed - she won three straight games to take the match to a decider.

Bertens broke twice consecutively in the third set to take her streak of winning games to seven as her attacking play at the net ruffled her Australian opponent. 

Despite Barty recovering one of the breaks, Bertens stayed calm to defeat a world No 1 for only the second time in her career.

The latter match was do or die for Bencic, and after saving break point in the sixth game of the first set, she took advantage of Kvitova’s errors to win just her third set against the Czech in her career.

But after some time away from the court, Kvitova seemed to reset magnificently, as she was able to back up her two breaks of serve with her first serve, on which she was winning 79% of the points at the time. 

Bencic was broken once more and for the fifth match out of six so far this week, a deciding set was required.

As has been the case throughout the week so far, the third set was filled with twists and turns as Bencic and Kvitova traded a brace of breaks each. 

But in the ninth game, a backhand cross court winner from Bencic gave her the important break and she served out the match.

Due to Bertens and Bencic winning, all four players in the Red Group still have a chance of qualifying when the final matches are played on Thursday.