Defending champion Angelique Kerber of Germany was knocked out of the U.S. Open in the first round when she lost 6-3 6-1 to Japanese teenager Naomi Osaka on Tuesday.
The last defending womenโs champion to lose in the first round at Flushing Meadows was Russian Svetlana Kuznetsova in 2005.
The 19-year-old Osaka, the 2016 WTA newcomer of the year, was rarely troubled by the sixth-seeded Kerber, who has not won a title since she prevailed here last year.
Osaka broke for 5-3 in the opening set and never looked back to claim her first victory against a top-10 player.