WTA Finals: Karolina Pliskova beats Simona Halep to join Elina Svitolina in semi-finals
Czech second seed Karolina Pliskova clinched the last spot in the WTA Finals semi-finals by beating Simona Halep in a dramatic elimination match.
Pliskova won 6-0 2-6 6-4 against the Romanian and faces Australian world number one Ashleigh Barty on Saturday.
Reigning champion Elina Svitolina kept up her 100% record with a hard-fought win over American Sofia Kenin.
Svitolina took her sixth match point to win 7-5 7-6 (12-10) after Kenin had a chance to serve out each set.
The 25-year-old Ukrainian was already assured of a semi-final spot and plays Swiss seventh seed Belinda Bencic on Saturday.
Kenin, 20, replaced the injured Bianca Andreescu on Thursday and had no chance of progressing to the last four.
After also earning straight-set wins over Halep and Pliskova, Svitolina had to show her fighting qualities to edge past Kenin in just over two hours.
With the winner joining Svitolina in the semi-finals, Pliskova also needed to dig deep to see off Wimbledon champion Halep in a strange match where momentum regularly switched between the players.
Pliskova, who is yet to convert being one of the consistently best players on the tour into a Grand Slam title, hit 11 winners and made just three unforced errors as she raced to the first set in just 20 minutes.
But Halep managed to neutralise Pliskova to fight back in the second set and take the match into a decider.
Like Pliskova in the opener, Halep won six games in a row to lead by a break in the third set before losing her way and being told she was "an absolute disgrace" by coach Darren Cahill in a startling on-court exchange.
Halep won just one point in the next two games to trail 5-2 and, after fighting back to 5-4, was broken again as Pliskova clinched victory with a forehand which took a chunk out of the net.
Former British number one Jo Durie, analysing the match for BT Sport, said she was shocked by Cahill's approach and thought it was "humiliating" for Halep.
"There are times when you need a kick but I thought it was too much," Durie said.
British coach Nigel Sears, who works with Estonian world number 25 Anett Kontaveit, added Cahill was "right in sentiment but too strong in delivery and wording".
The final in Shenzhen is on Sunday at 11:30 GMT.