World number one Simona Halep set up a headline last 16 showdown with Serena Williams by beating her sister Venus as Novak Djokovic's relentless drive towards more Australian Open glory cranked up another gear. On day six at Melbourne Park, the Romanian finally hit form to pull off her best win of the year and cruise past the veteran American 6-2, 6-3. "I was super-motivated today," she said after being taken to three sets in both her opening two matches as she bounces back from a herniated disc that ended her 2018 season early. "I have nothing to lose," she added, looking ahead to Monday's clash against 23-time Grand Slam winner Serena. "I playing against a great champion. Its's going to a bigger challenge but I'm ready to face it." Williams crushed Ukrainian Dayana Yastremska 6-2, 6-1 before consoling her at the net as the teenager burst into tears.
The ominous 37-year-old, seeded 16, has dropped just nine games in her three matches so far on her first return to the tournament since winning it in 2017 while pregnant. "I just play each match at a time, play as hard as I can and do the best I can. That really is all you can do," she said as she zeroes in on an eighth Australian title and a record-equalling 24th Slam crown.
Fourteen-time Grand Slam winner and top seed Djokovic is gunning for a record seventh Australian title. He dropped a set for the first time this year against fast-rising Canadian Denis Shapovalov, before demolishing him in the fourth stanza to win 6-3, 6-4, 4-6, 6-0. "I just tried to be in the moment and weather the storm," said the Serb, who was unsettled when the lights were switched on in Rod Laver Arena for television reasons, despite it still being daylight.
"Completely unnecessary to turn on the lights," he said in roasting the organisers. Djokovic's victory means he is guaranteed to stay world number one when the new rankings are released after the tournament.
He next plays another up-and-coming star, Russia's 15th seed Daniil Medvedev, who eased past David Goffin and has yet to drop a set. Another young gun Alexander Zverev made the last 16 for the first time when he swatted aside Australian Alex Bolt in three sets and will play former world number three Milos Raonic for a place in the quarter-finals.
Fourth seed Naomi Osaka looked down and out against Taiwanese veteran Hsieh Su-wei before battling back to win 7-5, 4-6, 6-1 and set up meeting with Latvia's Anastasija Sevastova.
'Die or win'
Osaka's win equals the 21-year-old's best performance at the Australian Open, where she reached the last 16 in 2018 but lost to Halep. But she looked headed for the exit when she conceded the first set and was down 4-1 in the second, before winning five straight games to force a decider.
"I just didn't want to give up," said the Japanese, who received a code violation after throwing her racquet.
Sixth seed Elina Svitolina struggled with a painful shoulder complaint that required treatment at every changeover, and medical timeouts, before she somehow beat China's Zhang Shuai 4-6, 6-4, 7-5 as the temperature rose in the centre court sunshine.
"I just told myself 'you're going to die or win'," said Svitolina, who scored her biggest career win by clinching the WTA Finals in Singapore last October.
She will next meet 17th-seeded American Madison Keys. Eighth seed Kei Nishikori made it back-to-back victories for Japan, following Osaka on court by beating Portugal's 44th-ranked Joao Sousa in three sets. The 29-year-old has won all three of his first week matches on Margaret Court Arena to reach the last 16 for the seventh time in nine appearances.
"I love to play this court," said the 2014 US Open finalist after delighting a large contingent of Japanese fans. He next plays Spain's 23rd seed Pablo Carreno Busta.