NEW YORK: Naomi Osaka's 10-match US Open winning streak and title defense are done after she was outplayed in the fourth round by Belinda Bencic and lost 7-5, 6-4.
Osaka has been wearing a black sleeve on her bothersome left knee and was visited by a trainer after getting broken to trail 3-2 in the second set.
The result under the closed roof at Arthur Ashe Stadium on a rainy Monday means both defending champions and No. 1 seeds are gone before the quarterfinals at the year's last Grand Slam tournament.
Novak Djokovic stopped playing in his fourth-round match against Stan Wawrinka on Sunday night because of a painful left shoulder.
Osaka made her breakthrough at Flushing Meadows a year ago, winning her first major championship by beating Serena Williams in a chaotic final that devolved after Williams got into an extended argument with the chair umpire.
Osaka followed that up with a second consecutive Grand Slam trophy at the Australian Open in January. That allowed her to become the first tennis player representing Japan to reach No. 1 in the rankings.
The 13th-seeded Bencic, who is from Switzerland and has been mentored by Martina Hingis, showed again that she is a big-match player. She improved to 3-0 against Osaka this season and now has a tour-leading nine victories over top-10 opponents in 2019.
Bencic also is 4-1 over her career against top-ranked players.