MELBOURNE, Australia (AP) The Latest from the Australian Open on Sunday (all times local):
Defending champion Angelique Kerber has joined fellow top-ranked Andy Murray on the sidelines of the Australian Open, losing 6-2, 6-3 to American CoCo Vandeweghe in the last match on Rod Laver Arena on Sunday.
Hours earlier, Murray was beaten in four sets by 50th-ranked Mischa Zverev. And the same court saw Kerber, who beat Serena Williams in the final last year, also drop out of the tournament in the fourth round.
Vandeweghe will next play French Open champion Garbine Muguruza in the quarterfinals.
Roger Federer may be one of the greatest tennis players of all time, but he'll freely admit - he's not the best singer.
After Federer's fourth-round win over Kei Nishikori, former Grand Slam winner Jim Courier interviewed him in Rod Laver Arena about the match and then surprised him with a special video that Federer had posted on Twitter the day before.
In the clip, Federer is singing Chicago's ''Hard to Say I'm Sorry'' with fellow players Tommy Haas and Grigor Dimitrov, while David Foster, who wrote the 1982 hit song, accompanied them on piano.
After a few seconds, Courier wanted to know who was off-key? Was it Federer?
''I thought it was terrible acoustics in that room,'' Federer said, laughing. ''I didn't even know that song that well. The lyrics were not my thing. My voice was playing up a little bit.''
Haas, however, knew the song well and saved the group, Federer said.
''I think he just looks good,'' Federer said. ''His voice is terrible.''
Roger Federer wasn't about to go the way of Andy Murray, rebounding from a slow start to beat fifth-seeded Kei Nishikori 6-7 (4), 6-4, 6-1, 4-6, 6-3 to advance to the Australian Open quarterfinals for the 13th time in 14 years.
Federer's match on Rod Laver Arena began not long after the day session crowd had cleared from top-seeded Murray's four-set loss to 50th-ranked Mischa Zverev. It turns out the biggest beneficiary of that loss will be Federer, who plays Zverez in the quarterfinals.
At first, it looked as if Federer might join Murray on the sidelines. He fell behind 4-0 and 5-1, rallied to level at 5-5 only to see Nishikori stage a resurgence in the tiebreaker.
Federer, playing his first official tournament since returning from a six-month layoff with a left knee surgery, had break points in the second and fourth games of the fourth set, but it was Nishikori who made the vital break to send it to a decider.
Trailing 3-0 in the final set, Nishikori called for a trainer and took a medical timeout for treatment on his back. Federer completed the win some 30 minutes later, breaking Nishikori's serve for the eighth time to end the match in 3 hours, 24 minutes.
Jo-Wilfried Tsonga has ended Daniel Evans' strong run at the Australian Open, beating the British player 6-7 (4), 6-2, 6-4, 6-4 to advance to the quarterfinals.
Evans had beaten 2014 U.S. Open champion Marin Cilic in the second round and local hope Bernard Tomic in the third before running into Tsonga, who lost the Australian Open final in 2008 to Novak Djokovic.
Tsonga next plays U.S. Open champion Stan Wawrinka, who had his major breakthrough in Australia in 2014.
French Open champion Garbine Muguruza needed just 65 minutes to beat Sorana Cirstea 6-2, 6-3 and advance to the quarterfinals at the Australian Open.
It is Muguruza's best finish in five trips to the Australian Open.
''It means a lot, I always come here very motivated,'' Muguruza said. ''To be in the quarterfinals is a great achievement. When you win one (major), you have that self-confidence and that belief in yourself that you can do it again.''
Muguruza's opponent in the quarterfinal will be determined later Sunday when defending champion and No. 1-ranked Angelique Kerber plays CoCo Vandeweghe.
U.S. Open champion Stan Wawrinka has advanced to the Australian Open quarterfinals in three tough sets over Andrea Seppi, winning 7-6 (2), 7-6 (4), 7-6 (4) on Margaret Court Arena.
Fourth-seeded Wawrinka, the 2014 Australian titlist, will face the winner of the later match between 2008 Australian Open finalist Jo-Wilfried Tsonga and Dan Evans.
Top-seeded Andy Murray is out of the Australian Open, beaten 7-5, 5-7, 6-2, 6-4 by 50th-ranked Mischa Zverev.
Murray, who has lost five Australian Open finals, dropped his serve eight times in the Rod Laver Arena afternoon match that went 3 hours, 34 minutes.
Zverev, a German lefthander and the older brother of Alexander Zverev, who lost to Rafael Nadal in the third round on Saturday, advances to a quarterfinal against the winner of the later match between Roger Federer and Kei Nishikori.
It's the first time since 2002 that neither the No. 1 nor the No. 2 seed has reached the Australian Open quarterfinals.
Murray joins six-time defending champion Novak Djokovic, beaten in the second round by wild-card entry Denis Istomin, on the sidelines for the second week at Melbourne Park.
Venus Williams has advanced to the quarterfinals at Melbourne Park for the second time in three years, beating Mona Barthel 6-3, 7-5.
Williams broke Barthel's serve in the 11th game of the second set and served out, clinching the 1-hour, 36-minute fourth-rounder on her first match point.
Williams, who lost the 2003 final at Melbourne Park to her younger sister Serena, will next play Anastasia Pavlyuchenkova, who beat fellow Russian Svetlana Kuznetsova in straight sets earlier Sunday.
Since losing that final in `03, Venus advanced to the quarterfinals three other times in Melbourne, but hasn't got past that stage.
Anastasia Pavlyuchenkova is the first player through to the quarterfinals at the Australian Open, beating two-time Grand Slam champion Svetlana Kuznetsova 6-3, 6-3 in a fourth-round match at Rod Laver Arena.
Pavlyuchenkova led 2-0 in the second set before Kuznetsova broke back. Pavlyuchenkova then broke her fellow Russian's serve again at 3-all, and once more in the final game, clinching the match in 68 minutes on her second match point when Kuznestova hit a forehand into the net.
''I'm kind of shocked a little,'' she said afterward. ''But at the same time, so happy.''
Pavlyuchenkova will play either Venus Williams or Mona Barthel in the quarterfinals. Williams and Barthel play the next match at Rod Laver.
Defending champion Angelique Kerber and four-time winner Roger Federer attempt to book quarterfinal spots Sunday on Day 7 of the Australian Open.
Under sunny skies and an expected high temperature of 30 degrees Celsius (86 Fahrenheit), two-time major champion Svetlana Kuznetsova kicked things off at Rod Laver Arena with a fourth-round match against fellow Russian Anastasia Pavlyuchenkova.
Following that match, Venus Williams was scheduled to play Mona Barthel. Top-seeded Andy Murray has the last match on the main court, playing Mischa Zverev.
Federer was set to take on Kei Nishikori in a night match, followed by Kerber's match against CoCo Vandeweghe of the United States.
Also in action was U.S. Open champion Stan Wawrinka, playing Andreas Seppi in an afternoon match at Margaret Court Arena.