Australian Open updates: Simona Halep sets up Serena Williams clash in last 16

World No 1 Simona Halep insisted she will have nothing to lose when she takes on Serena Williams in the fourth round of the Australian Open. After battling through two tough opening rounds against Kaia Kanepi and Sofia Kenin, Halep knew she would have to step things up against Venus Williams and she did so impressively in a 6-2, 6-3 victory. In what must surely be the toughest draw a top seed has ever faced, Halep now finds herself taking on Serena, who has lost only nine games in three matches and demolished 18-year-old Dayana Yastremska 6-2, 6-1. Halep may have the number one next to her name but she has won only one of her nine previous meetings with Serena and feels she goes in as the underdog. The Romanian said: "In my opinion, to be No 1 in the world and to be the best player in the world, it's a little bit different. In this moment, I'm number one in the world, so I will take that." Czech seventh seed Karolina Pliskova battled through to the last 16 with a tough three-set win over Italy's Camila Giorgi. Pliskova downed the 27th seeded Italian 6-4, 3-6, 6-2 after a 131-minute arm wrestle to set up a fourth round meeting with Spanish 18th seed Garbine Muguruza. Former world No 1 Pliskova took the first set at a canter and appeared to be cruising until Giorgi lifted in the second and forced a decider. The Czech took a decisive break early in the final set after a marathon game that went for 13 minutes and went to deuce five times. "I had trouble sometimes but I just stayed calm even though I lost the second set. I had my chances but that's tennis," she said. "I was very positive in the third set and I'm very happy to be through." Top seed Novak Djokovic angrily blamed floodlights for dropping a set for the first time at this year's Australian Open after beating Denis Shapovalov 6-3, 6-4, 4-6, 6-0 on Saturday. The Serb is looking for a record seventh Aussie crown but was left fuming when leading 3-0 in the third set against the 25th-seeded Canadian when the powerful lights blazed on all around Rod Laver Arena -- in bright sunshine. An irritated Djokovic lost his focus completely and dropped six of the next seven games after querying French umpire Damien Dumusois why the lights were on. "I think there was no sense to turn on lights on court at 5pm when we have another four hours of daylight," fumed the Serb 17-time Grand Slam winner. "Did you guys see the balls well?," he asked the crowd. "I saw them well too," he said to a huge cheer. "Completely unnecessary to turn on the lights. The explanation I got was for TV reasons. I hope the viewers enjoyed it," he added. Milos Raonic and Madison Keys enjoyed straight sets wins to reach the fourth round. Canada's Raonic, the 16th seed, beat Pierre-Hugues Herbert 6-4, 6-4, 7-6. The American Keys defeated Elise Mertens 6-3, 6-2 to set up a fourth-round clash with Elina Svitolina. Former world No 3 Raonic had needed four tiebreaks and four hours to see off former Australian Open champion Stan Wawrinka in Round 2, but the Canadian was in no mood to hang about on Saturday. The big server, who reached the semi-finals in Melbourne in 2016, was never behind as he sped through the last-32 clash in just 121 minutes. "I took yesterday off and didn't come on to a tennis court, after four hours on one on Thursday," Raonic said. "I came out fresh and glad to have another match in two days." Serena Williams swatted aside Ukrainian teenager Dayana Yastremska in straight sets on Saturday, powering into the last 16 as she chases a record-equalling 24th grand slam title. Williams defeated world No 57 Yastremska 6-2, 6-1 and next faces either sister Venus, who is unseeded this year, or world No 1 Simona Halep. The 37-year-old won her 23rd major in Australia two years ago while two months pregnant and is hoping to claim an eighth Australian title, despite being seeded 16th. Another major would match Margaret Court's tally and Williams looks in ominous form as she chases down the Australian great's record, dropping only nine matches in her opening three matches. "I'm here, I'm playing as hard as I can and doing the best I can, which is really all I can do," she said. Her latest victim Yastremska was not even born when the American won her first major at Flushing Meadows in 1999. The 18-year-old was in tears after her drubbing and Williams comforted her at the net, telling her "you're gonna make it, don't cry". "I thought she did really amazing," Williams said of the youngster. "She came out swinging, I felt like she really came out ready to go." Kei Nishikori made it back-to-back victories for Japan on Saturday by sweeping into the fourth round. The in-form eighth seed felt his way into the first set against Portugal's 44th-ranked Joao Sousa before romping away to a 7-6, 6-1, 6-2 win in 2hr 6min. He was preceded onto Margaret Court Arena by countrywoman and US Open champion Naomi Osaka, who fought back from a set down to battle past Taiwan's Hsieh Su-wei. The 29-year-old Nishikori has won all three of his first week matches on the same Melbourne Park second showcourt to reach the last 16 of the Australian Open for the seventh time in nine appearances. "I love to play this court, I'm very comfortable here," said the 2014 US Open finalist after delighting a large contingent of Japanese fans. "It's great to play here, especially after Naomi today." Naomi Osaka and Elina Svitolina survived big scares but displayed fighting qualities to pull back from the brink. Fourth-seeded 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 a last-16 meeting with Latvia's Anastasija Sevastova, who beat China's Wang Qiang in straight sets. Svitolina struggled with a painful shoulder complaint that required treatment at every change of ends, and medical timeouts, before somehow beating China's Zhang Shuai 4-6, 6-4, 7-5 as the temperature rose in the centre court sunshine. Victors also winning hearts Osaka's win equals the 21-year-old's best performance at the Australian Open, where the Japanese star reached the last 16 in 2018 but lost to Simona 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 made 42 unforced errors and received a code violation after throwing her racquet. "I really love grand slams so I did anything I could do to stay here a bit longer." Ukrainian Svitolina also staged an epic fightback and shrugged off an injury scare to reach the fourth round. Svitolina, who scored her biggest career win by clinching the WTA Finals in Singapore last October, received treatment on her neck and shoulder twice during the victory. "It was very hot conditions, I was struggling a little bit. We left everything on court today. We practise every day for these kind of matches," she said, watched by boyfriend Gael Monfils. "I just told myself 'you're going to die or win'. It was a mental game. I had to stay strong. "We were fighting until the last point. I was just trying to stay out there as long as possible." She will meet 17th seeded American Madison Keys in the next round. ______________ Read more: Hewitt accuses Tomic of blackmail and physical threats as Davis Cup fall-out continues Will Roger Federer hold off Novak Djokovic to retain title? Australian Open predictions Novak Djokovic and Serena Williams chase milestones: Australian Open talking points ______________ Rising star Daniil Medvedev cruised into the last 16 of a Grand Slam for the first time Saturday to set up a potential Australian Open showdown with Novak Djokovic. The Russian 15th seed breezed past seasoned Belgium David Goffin 6-2, 7-6 (7/3), 6-3 in two hours on Melbourne Arena. The 22-year-old Medvedev is fast becoming a force to be reckoned with, breaking into the world's top 20 for the first time in October and reaching the final of the Brisbane International two weeks ago. His breakthrough 2018 began in Australia 12 months ago when he won the Sydney International as a qualifier to lift his first ATP Tour title. He pulled out of his title defence this year with a right shoulder problem but has had no issues in Melbourne, flying impressively into the second week without dropping a set. "I was playing a good player today," he said. "I had a few tough moments on serve. "I had my first best result in Australia last year and now I'm in the fourth round of a Grand Slam for the first time. I love Australia," he added.

Australian Open updates: Simona Halep sets up Serena Williams clash in last 16

Halep beats Serena's sister Venus in third round, plus round-up of other action from season's first major in Melbourne