Pliskova wins the 'head' game, Serena denies 'choking'

Karolina Pliskova said saving four match points against Serena Williams had got into the American's "head" as the Czech completed an epic comeback win to reach her first Australian Open semi-finals on Wednesday.

Seventh seed Pliskova saved a match point at 5-1 down in the deciding set and another three at 5-4 before Williams crumbled 4-6 6-4 7-5 in front of a stunned crowd at Rod Laver Arena.

The nerve-jangling win booked the tall Czech her first Melbourne semi-finals and she will meet U.S. Open champion Naomi Osaka for a place in the title-decider.

Pliskova described the victory as the comeback of her life but one that wouldn't have happened without some assistance from her 23-times Grand Slam champion opponent.

"She was already match point up in that 5-1 game. Lots of things happened ... in those games. I just felt a chance," she told reporters.

"I think she maybe got little bit, I don't know, for sure it was in her head. Lots of things happen.

"I saw a chance and I just took it."

The big-serving Czech was brilliant in the face of defeat, capturing the decisive break in the 11th game before sealing the win on a third match point when Williams slapped a forehand into the net, her 37th unforced error.

Having avenged her loss to Williams at the U.S. Open quarter-finals, Pliskova now has an enviable Grand Slam record against the American great, having beaten her in two of their three matches at the majors.

Pliskova toppled Williams at the 2016 U.S. Open semi-finals when the American was top seed but felt the 37-year-old Williams she faced at Melbourne Park had played better.

"I think honestly she played much better than when she was playing when I beat her in New York. The match was so much better.

"There were more mistakes (in New York). Maybe she was nervous, it was in States."

Pliskova, who reached world number one in 2017 but has yet to claim a Grand Slam title, has a chance to regain the top ranking if she wins the tournament.

Her next opponent Osaka and compatriot Petra Kvitova, who faces Danielle Collins in the next match, are also in the running to be crowned number one.

"I don't want to say it means zero, but it doesn't mean the same. Right now in this situation (it) would not mean the same as winning the Grand Slam," she said.

"I'm not going to chase this, so for me nothing is changing."

Pliskova has won two out of three of her matches against Osaka. She fell to the hard-hitting 21-year-old in the quarter-finals at Indian Wells last year before beating her in front of home fans in their last meeting at the Japan Open title-decider.

"Yeah, I've played a few hitters here in the last matches, obviously Camila Giorgi, now Serena. I think I'm well prepared for Naomi," said 26-year-old Pliskova.

"If I play well, I think for sure there is a chance."

Beaten Williams denies 'choking' after shock exit

A disappointed Serena Williams denied "choking" in her stunning quarter-final loss to Karolina Pliskova at the Australian Open on Wednesday after failing to convert four match points and surrendering a 5-1 lead in the deciding third set.

The seven-times champion lost a match point at 5-1 and saw another three disappear at 5-4 before crumbling to a 6-4 4-6 7-5 defeat to seventh seed Pliskova at Rod Laver Arena.

"It's kind of hard to say because she -- there's nothing I did wrong on those match points," Williams told reporters after her bid for a record-equalling 24th Grand Slam title ended.

"I didn't do anything wrong. I stayed aggressive. She just literally hit the lines on some of them.

"One she hit an ace, unreturnable serve. Like I literally did everything I could on those match points.

"It's not like -- yeah, I can't say that I choked on those match points. She literally played her best tennis ever on those shots."

After serving an ace to bring up the first match point at 5-1, Williams rolled her ankle and put a forehand into the net.

At 5-4, serving to stay in the match, Pliskova saved the second with a searing backhand winner.

Williams lost the third and fourth match points in near-identical fashion, netting forehands after being pushed into the corner by the desperate Pliskova.

From there, the American's dominant serve wavered as she double-faulted to fall to 0-30 at 5-5, and she was broken by an unforced error, allowing Pliskova to serve for the match.

Williams claimed her 23rd Grand Slam title while two months' pregnant at the 2017 Australian Open but has fallen agonisingly short of another since coming back from maternity leave.

She was beaten by Angelique Kerber in the Wimbledon title-decider and by Naomi Osaka in the controversial U.S. Open final in which she had a major row with the chair umpire.

Williams, seeded 16th at Melbourne, said she would keep "soldiering on" and continue her bid to match Margaret Court's record of 24 Grand Slam titles at the French Open.

Only 10 months into her comeback, the 37-year-old said she felt her she was still short of her best tennis.

"It's hard to say because, like I said, from the first tournament I'm thinking that I should win, which is not practical," she said.

"But I know there's a lot of things that I need to do, a lot of things I need to do to get better, a lot of maybe more just matches.

"I just feel like, as close as I want to say that I'm there, I know that there's a lot more that I need to do to kind of get there. 10 months, soon to be 11 months, soon it will be 12 months. It just takes time."

Some 24 years after turning professional in 1995, Williams said she would absorb the match point lesson from Pliskova.

"Next time I'm up 5-1 against anybody, whether it's her or anyone, I just need to make sure I play lights out when I have match points," she said.

"The next time that I have match point ... just go bananas on it."