Darren Cahill’s tough love couldn’t save Simona Halep as world No.2 Karolina Pliskova set up a semi-final showdown with Ashleigh Barty at the season-ending showpiece in Shenzhen.

One of tennis’s most respected coaches, Cahill was savaged on social media for branding Halep “an absolute disgrace” during the Wimbledon champion’s 6-0 2-6 6-4 capitulation to Pliskova on Friday night.

Pliskova’s rollercoaster victory earned her second spot in the Purple Group with a 2-1 win-loss record for the week, with defending champion Elina Svitolina earlier marching into the semi-finals unbeaten after downing Sofia Kenin 7-5 7-6 (12-10).

Svitolina will face Belinda Bencic in Saturday’s first semi-final, before Barty bids to become the first Australian to reach the championship match since Evonne Goolagong Cawley in 1978.

But it was Cahill’s controversial courtside rev-up to Halep that overshadowed the on-court action.

Minutes after telling Halep he was proud of her for squaring the match up after being bagelled in the first set, Cahill returned to condemn her for meekly surrendering up a 2-0 lead in the decider.

“Simo? Simo, look at me. The last three games you’ve been an absolute disgrace on court,” the Australian said.

“Give yourself a chance by pulling yourself back in. This is on you. Get your attitude back on track and you will win this match. I have full belief.

“You have a choice here how to define yourself as an athlete and a competitor. It’s not about the result. It’s about how you finish this match.”

After dropping her very next service game to love, then falling behind 5-2, Halep broke back and led 30-love while trying to level the set at 5-5.

But the Romanian again lost four straight points on serve as Pliskova – having endured her own mid-match meltdown and conceding six consecutive games – eventually claimed a dramatic victory.

Svitolina told the WTA: “Each time I step on the court I have to win. My parents raised me this way – that I have to fight for everything, I have to give 100 per cent each time I play.”

Unlike Pliskova and Halep’s cut-throat affair, Svitolina had already sealed her place in the semi-finals.

But the Ukrainian still fought tooth and nail against Kenin, saving two set points in the second set, before finally clinching victory on her sixth match point in an epic tiebreaker.