Jan. 20 (UPI) -- It took less than an hour for three-time major champion Angelique Kerber to fall in stunning fashion to Danielle Collins 6-0, 6-2 in the most notable upset of the Australian Open's fourth round Sunday in Melbourne.
Collins, a University of Virginia product, next faces wither 2017 U.S. Open champion Sloane Stephens or Anastasia Palyuchenkova next.
In another women's fourth-round match, Maria Sharapova dropped a 4-6, 6-1, 6-4 decision to Aussie Ashleigh Barty.
Sharapova won this event in 2008 and defeated champion Caroline Wozniacki in the third round this year, but fell Sunday after a highly competitive 2-hour and 22-minute match that ended with a Barty ace.
Barty will now face Petra Kvitova, the two-time Wimbledon champion who topped 17-year-old American Amanda Anisimova in straight sets Sunday.
In men's action, No. 2 Rafael Nadal advanced to the quarterfinals courtesy of a 6-0, 6-1, 7-6 (4) win over Tomas Berdych. Nadal coasted in the first two sets before Berdych tested him in the third.
Also, American Frances Tiafoe advanced to the first Grand Slam quarterfinal of his career by topping Grigor Dimitrov 7-5, 7-6 (6), 6-7 (1), 7-5. Tiafoe's big victory took place on his 21st birthday.