No. 1 Angelique Kerber upset by American CoCo Vandeweghe at Australian Open

Defending Australian Open champion Angelique Kerber was upset by American CoCo Vandeweghe in the fourth round at the Australian Open.

Defending Australian Open champion Angelique Kerber was upset by American CoCo Vandeweghe in the fourth round at the Australian Open on Sunday.

World No. 35 Vandweghe prevailed 6-2, 6-3 in one hour and eight minutes, sending home World No. 1 Kerber and advancing to her first quarterfinal in Melbourne and only her second Grand Slam quarterfnal of her career (Wimbledon, 2015). With the loss Kerber became the second top seed to crash out in the fourth round, as fellow No. 1 Andy Murray lost to Mischa Zverev in four sets earlier in the day on Sunday.

"I think it's my first win over a world No. 1 I guess. I'll take it," Vandeweghe said on court after the match. "I faked it a lot, because I was feeling a bit crap out there. You have to fake it until you make it. I just had to pick my spots and trust my game."

For Kerber, the loss is her third of the year—she lost to Elina Svitolina in Brisbane and Daria Kasatkina in Sydney ahead of the Australian Open—and it puts her top ranking up for grabs. No. 2 Serena Williams can overtake Kerber in the top spot only if she wins the Australian Open. Sunday's loss also ends Kerber's 10-match winning streak in Melbourne, dating back to her 2016 run to the title.

Vandeweghe will next face No. 7-seed Garbine Muguruza and looks to one up her best-ever performance at a Grand Slam.​