A round-up of the men's and women's quarter-final action at Melbourne Park
Australian Open Day 10: Federer sets up semi-final clash against Chung, wins for Kerber and Halep
Defending champion Roger Federer swept into his 14th Australian Open semi-final with an immaculate straight sets win over Tomas Berdych on Wednesday.
Second seed Federer cruised to a 7-6, 6-3, 6-4 win and will face unseeded South Korean Chung Hyeon in Friday's semi-final.
Halep too good for Pliskova
World No 1 Simona Halep overcame a nervous start to thrash sixth seed Karolina Pliskova in their Australian Open quarter-final.
The Romanian reeled off nine games in a row and 12 of the last 14 games to recover from 0-3 en route to a 6-3, 6-2 victory on Rod Laver Arena.
"It's really nice to be in the semis," Halep said after moving into the last four at Melbourne Park for the first time, where she will face 2016 champion Angelique Kerber.
"For sure it wasn't my best start but I knew I had to restart after three games to stop missing and move better," said Halep, whose relentless chasing and powerful groundstrokes overwhelmed her taller opponent.
"I started to open the court and play my style, and I served well today. Everything went pretty much my way."
Kerber finds 2016 form to thrash Keys
Angelique Kerber has warned she is getting close to the 2016 form that saw her rule women's tennis after the German raced into the Australian Open semi-finals on Wednesday.
Kerber rose to No 1 in the world two seasons ago during a year in which she won two grand slam titles - at the Australian Open and the US Open. However, a frustrating 2017 resulted in a slide down the rankings and she entered this year's tournament in Melbourne seeded No 21.
But Kerber has so far provided plenty of evidence that she is rediscovering her old magic, and after going unbeaten at the Hopman Cup and winning the Sydney Open, the 29-year-old German has cruised into the last-four of the first grand slam of the season.
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Kerber needed just 51 minutes to dismantle last year's US Open finalist Madison Keys 6-1, 6-2, breaking the American's much-vaunted serve at will.
"I know that I was working hard in the off-season, and I know that I can play good matches. I'm just trying to find the feeling back I had like 2016," said Kerber, who will return to the top 10 in the world rankings.
"I just try to enjoy myself again on court. You know, I had a tough last year," said the German. "I'm proud how I got through all the last weeks and being in the semis again in a Grand Slam. So I'm feeling good."
Kerber will next face either top seed and world No 1 Simona Halep or sixth seed Karolina Pliskova for a place in the final.
Chung makes history
Unseeded Hyeon Chung became the first South Korean to reach a semi-final at a grand slam with a dominant straight sets win over American Tennys Sandgren.
Ranked 58, Chung needed six match points before claiming a 6-4, 7-6, 6-3 win and will face either defending champion Roger Federer or Tomas Berdych in Friday's semi-final.
Chung is the first South Korean man or woman to reach the semi-finals at a major and the youngest at 21 since Russia's Marat Safin reached the last four in Melbourne in 2010.
He joins Briton Kyle Edmund as the first unseeded men's semi-finalists in Melbourne since Frenchman Jo-Wilfried Tsonga in 2008.
In a tense 11-minute final game he claimed victory on his sixth match point after Sandgren threw everything at the South Korean in a bid to stay in the match.
"In the last game at 40-0 up I was thinking what I had to do at the ceremony, something like that, and after the break points I was like, nothing to do with ceremony, but just keep playing, stay focused," Chung said on court in his limited English.
Asked who he wanted to face in the semi-final, Federer or Berdych, Chung replied diplomatically with a smile: "It's 50-50."