Singapore: Karolina Pliskova became the first woman to advance to the last four of the WTA Finals when the big-hitting Czech put on a controlled display to defeat compatriot Petra Kvitova 6-3, 6-4 in their final round robin encounter on Thursday.
The former world number one will be joined in the last four by either Elina Svitolina (2-0) or defending champion Caroline Wozniacki (1-1), who complete White Group play at the Singapore Indoor Stadium later on Thursday.
Kvitova (0-3) had lost her opening two matches and knew that only a straight sets victory would give her any chance of advancing but Pliskova (2-1) stayed calm and focused to record a first win over her compatriot in four attempts.
"I cannot be more happy right now. It was a good match and she's a great player. She has always beaten me in the past but I knew I had a chance as I have been playing well," Pliskova said in a post-match interview.
"I'm not thinking about the next match yet, I'll do what I can to recover first. Before the tournament, I said to myself that I want to enjoy it and I will continue to do just that."
Kvitova needed to make a fast start to put her opponent under pressure but the double Wimbledon champion lacked movement and coughed up a slew of double faults to fall 4-0 down in the blink of an eye as Pliskova pounced on every opportunity.
Slowly but surely, Kvitova worked her way back into the contest, rallying twice from 40-0 down to win back-to-back games in the middle of the set that finally gave Pliskova something to think about.
Pliskova's coach Rennae Stubbs urged her to "stay disciplined" in the next changeover and the Czech heeded the advice to curb her attacking instincts as she ended Kvitova's tournament by holding serve to take the opener in 41 minutes.
The loss of the opening set appeared to free up Kvitova's booming forehand and she feasted on Pliskova's tentative start to the second set to race to a 3-0 lead, but the world number eight battled back brilliantly to book her semi-final place.
In the late match, Ukraine's Svitolina will advance if she wins one set against Wozniacki, who needs a straight-sets triumph to continue her title defence.
"We have problems on the other end of the pitch but tonight we were very solid defensively. The second half was just one-way traffic, we just dominated the second half. The Delhi goalkeeper won the man of the match and he kept Delhi in the match," he said.
Asked to elaborate on his team's defensive display against Delhi having conceded eight goals in their first three games, the Englishman said: "I was delighted we got a clean sheet from the game. Clean sheets are always welcome at any given stage and the coaches love them, fans probably don't love them, especially 0-0 games."
"But, we are delighted to keep a clean sheet. As you said, in the last two games we conceded eight goals which is not like us. Our team was built on a solid defence last year, we were really hard to play against. We were really strong defensively, we didn't give goals easily," he added.
"If anyone scored a goal against us they had to work really hard and it had to be something special. We had eight clean sheets and I hope we get that this time too. We need 29 points to get in the play-offs and I hope we do it."