<p> World number ones Andy Murray and Angelique Kerber both crashed out of the Australian Open on a day of major upsets Sunday, as Roger Federer fought his way closer to an 18th Grand Slam title.<br /><br /></p>.<p>Murray was stunned by 50th-ranked serve-and-volley specialist Mischa Zverev in four sets before Kerber, the women's title-holder, tamely succumbed 6-2, 6-3 to Coco Vandeweghe.<br /><br />The unpredictable results, following six-time champion Novak Djokovic's stunning loss in the second round, opened the door to a host of challengers -- with Federer leading the charge.<br /><br />The 35-year-old Swiss won the last of his record 17 Slam titles in 2012, but he took full advantage of Murray's demise with a 6-7 (4/7), 6-4, 6-1, 4-6, 6-3 win over Kei Nishikori.<br /><br />Federer, who looks back to full fitness after a six-month injury lay-off, said the hard-fought, fourth-round win could be significant as he now eyes a quarter-final with Zverev.<br /><br />"This is a huge moment for me in my career," Federer said.<br />"I was telling myself, 'Stay calm'. I feel fit, I've trained as hard as I possibly can in the off-season. That's what you tell yourself and you hope it pays off," he added.<br /><br />Murray had been the hot favourite after Djokovic's shock exit, but the Briton lost 7-5, 5-7, 6-2, 6-4 to Germany's Zverev to extend his wait for a first Melbourne title.<br /><br />The Briton was never expected to be troubled by the 29-year-old, who has never won an ATP title, but he suffered his earliest Melbourne departure in eight years.<br /><br />It isn't since the 2004 French Open that the top two men's seeds have gone out before the quarter-finals, and for Murray, a five-time losing finalist, it meant yet more Melbourne misery.<br /><br />"I've had tough losses in my career in the past. I've come back from them. This is a tough one," Murray said.<br /><br />"I'm sure I'll come back okay from it. But right now I'm obviously very down because I wanted to go further in this event, and it wasn't to be." <br /></p>
<p> World number ones Andy Murray and Angelique Kerber both crashed out of the Australian Open on a day of major upsets Sunday, as Roger Federer fought his way closer to an 18th Grand Slam title.<br /><br /></p>.<p>Murray was stunned by 50th-ranked serve-and-volley specialist Mischa Zverev in four sets before Kerber, the women's title-holder, tamely succumbed 6-2, 6-3 to Coco Vandeweghe.<br /><br />The unpredictable results, following six-time champion Novak Djokovic's stunning loss in the second round, opened the door to a host of challengers -- with Federer leading the charge.<br /><br />The 35-year-old Swiss won the last of his record 17 Slam titles in 2012, but he took full advantage of Murray's demise with a 6-7 (4/7), 6-4, 6-1, 4-6, 6-3 win over Kei Nishikori.<br /><br />Federer, who looks back to full fitness after a six-month injury lay-off, said the hard-fought, fourth-round win could be significant as he now eyes a quarter-final with Zverev.<br /><br />"This is a huge moment for me in my career," Federer said.<br />"I was telling myself, 'Stay calm'. I feel fit, I've trained as hard as I possibly can in the off-season. That's what you tell yourself and you hope it pays off," he added.<br /><br />Murray had been the hot favourite after Djokovic's shock exit, but the Briton lost 7-5, 5-7, 6-2, 6-4 to Germany's Zverev to extend his wait for a first Melbourne title.<br /><br />The Briton was never expected to be troubled by the 29-year-old, who has never won an ATP title, but he suffered his earliest Melbourne departure in eight years.<br /><br />It isn't since the 2004 French Open that the top two men's seeds have gone out before the quarter-finals, and for Murray, a five-time losing finalist, it meant yet more Melbourne misery.<br /><br />"I've had tough losses in my career in the past. I've come back from them. This is a tough one," Murray said.<br /><br />"I'm sure I'll come back okay from it. But right now I'm obviously very down because I wanted to go further in this event, and it wasn't to be." <br /></p>