MELBOURNE, Australia (AP) Venus Williams has returned to the quarterfinals for the ninth time at the Australian Open, where she first made the last eight on debut in 1998.
The 36-year-old, seven-time major winner had a 6-3, 7-5 fourth-round win Sunday over No. 181-ranked Mona Barthel, who won three matches in qualifying and then beat two Australian wild cards and Olympic gold medalist Monica Puig in the first three rounds.
Williams will next play No. 24-seeded Anastasia Pavlyuchenkova, who beat No. 8 Svetlana Kuznetsova 6-3, 6-3 in the opening match of Day Seven at Rod Laver Arena.
Pavlyuchenkova's win over fellow Russian Kuznetsova left Williams as the only Grand Slam winner left in that quarter of the draw.
''I was really challenged to play my best tennis,'' Williams said. ''It's wonderful to get through to the quarterfinals against an opponent who's on fire.''
Williams hasn't advanced beyond the quarterfinal round at Melbourne Park since her loss to younger sister, Serena, in the 2003 final. But she hasn't lost a set en route to the quarterfinals this year. Against Barthel, she won 90 percent of points when she got her first serve into play, hit 31 winners and four aces while not serving any double-faults.
''This is what you do all the hard work in the off-season for,'' she said. ''It's wonderful to be able to advance even further.''
Barthel was the lowest-ranked player to reach the fourth round of the women's draw here since 2010, although she has a career-high ranking of 23 and was consistently top 50 before an illness last year caused her slide down the rankings.
''I know what it's like to be down on my luck,'' Williams said. ''We've played a couple of touch matches before. Today I expected to have some competition.''
Defending champion and No. 1-ranked Angelique Kerber was playing CoCo Vandeweghe in the last night match.
It's a lot more crowded on the top quarter of the men's draw, which features matches later Sunday involving top-ranked Andy Murray against Mischa Zverev and Roger Federer against Kei Nishikori.