The Latest from the Australian Open on Sunday (all times local):
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.