Australian Open updates: Novak Djokovic and Serena Williams reach quarter-finals

Novak Djokovic dropped a set for the second match running but survived a tough examination by 15th seed Daniil Medvedev on Monday to reach the Australian Open quarter-finals. The world No 1 won 6-4, 6-7, 6-2, 6-3 and will face Japan's eighth seed Kei Nishikori for a place in the semi-finals. Djokovic and Medvedev both needed attention from the trainer during a draining 3hr 15min match liberally sprinkled with punishing rallies of 30 shots or more, and one of 42 strokes. "That was a physical battle," said a relieved Djokovic, who crucially saved three break points from 2-1, 0-40 in the pivotal third set to break the tenacious 22-year-old's resolve. "Daniil played some great tennis. He has a great backhand and doesn't make any unforced errors on that side. It was hard to find another way to get through him. In these kinds of matches you just have to hang in there." Serena Williams continued her bid for a record-equalling 24th grand slam title after beating top seed Simona Halep in a thrilling fourth round encounter. Williams, a seven-time champion in Melbourne, looked set to steamroll into the quarter-finals after taking the first set 6-1 in just 21 minutes. However, Halep fought her way back to claim the second set and appeared in the ascendancy in the decider, only to drop her serve to allow Williams to win 6-1, 4-6, 6-4. Williams will next face seventh seed Karolina Pliskova for a place in the semi-finals. A slow-starting Lucas Pouille rallied from a set down to overcome Borna Coric 6-7, 6-4, 7-5, 7-6 and advance to the quarter-finals for the first time. The Frenchman made hard work of the fourth set, allowing 11th seed Coric to break back and drag the match into a tiebreak in the twilight at Melbourne Arena. Pouille raised his game when it mattered, however, flicking a delightful lob over Coric to move within two points of victory. The 28th seed Pouille grabbed four match points when Coric netted a volley and converted the first of them when the Croat hammered a shot over the baseline. Pouille will meet 16th seed Milos Raonic for a place in the semi-finals. Karolina Pliskova thrashed two-time grand slam champion Garbine Muguruza 6-3 6-1 to reach quarter-finals for the third time in succession. The Czech seventh seed broke former Wimbledon champion Muguruza five times in the one-sided clash in the afternoon sunshine at Margaret Court Arena. Needing only 24 minutes to win the second set, Pliskova earned two match points on Muguruza's serve and sealed the win when the out-of-sorts Spaniard smashed a backhand long. Pliskova will meet the winner of top seed Simona Halep and Serena Williams for a place in the semi-finals as she continues her bid for a maiden grand slam. Milos Raonic kept his cool to reach the quarter-finals as Alexander Zverev went into meltdown and crashed out of the Australian Open. The fourth seed erupted in frustration during the second set of a 6-1, 6-1, 7-6 drubbing by the Canadian 16th seed, hammering his racket into the ground eight times to leave it a mangled mess. "I just tried to stay composed, "said Raonic. "It worked extremely well for me today. I played incredibly good, did a lot of things extremely well." Zverev has long been tipped as a future grand slam champion after a breakthrough 2018 that saw him win the ATP Tour Finals, beating Novak Djokovic and Roger Federer in the process. Instead it was a familiar tale of woe as his much vaunted-talent deserted him again before he could reach the sharp end of a major. The 21-year-old's underwhelming major record in was extended to just one quarter-final, at the French Open last year, in 15 appearances. All seemed well when the world No 4 broke former world No 3 Raonic's formidable serve in the opening game of the match. But he then lost the next nine in an error-strewn display. Zverev committed eight double faults and 16 unforced errors against only eight winners as the first two sets evaporated in 63 minutes. He stopped the flood of mistakes in the third set and took it to a tiebreak, saving two match points along the way. But it was too little, too late as Zverev's abject record in Slams continued. Raonic will next face either Croatia's 11th seed Borna Coric or 28th seed from France Lucas Pouille for a place in the semi-finals. ___________ Read more: Stefanos Tsitsipas 'happiest man on earth' after win over Roger Federer Rafael Nadal wary of 'dangerous' Frances Tiafoe ahead of quarter-final ___________ Japanese fourth seed Naomi Osaka edged past 13th seed Anastasija Sevastova of Latvia in three sets to set up a quarter-final clash with Elina Svitolina. The US Open champion triumphed 4-6, 6-3, 6-4 to keep alive her dream of a second successive grand slam title. It is the second time in a row the 21-year-old has been forced to come back from a set down after struggling to overcome Taiwan's Hsieh Su-Wei in the previous round. "I didn't give up, she was playing really well and I wasn't really sure what to do at a certain point but I just tried to stick in there," Osaka said. "I was thinking I've been in this position before - actually it was a little bit worse last time." Sixth seed Elina Svitolina dug deep to overcome 17th seeded American Madison Keys 6-2, 1-6, 6-1 to reach the quarter-finals for the second time in a row. Keys, a US Open finalist in 2017, started slowly but came back to take the second set and put Svitolina under pressure at the start of the third. The turning point was a marathon 16-minute game early in the deciding set that went to deuce 11 times as Keys chased a decisive break. But the American's resolve crumbled when Svitolina held off five break points then gained an advantage in the next game. "I had to put my level up, I'm glad I handled the pressure," said Svitolina, who scored her biggest career win at the WTA Finals in Singapore last October. "It was very hard because the sun was burning my eyes when I was tossing the ball, so I was very happy to win."

Australian Open updates: Novak Djokovic and Serena Williams reach quarter-finals

A round-up from the fourth round at Melbourne Park, on a day headlined by Simona Halep's clash with Serena Williams