Osaka suffers shock loss in U.S. Open third round

Two-time champion Naomi Osaka suffered a stunning defeat in the third round of the U.S. Open on Friday to Canadian Leylah Fernandez 5-7 7-6(2) 6-4, ending her title defence inside Arthur Ashe Stadium.

Playing in her first Grand Slam since pulling out of the French Open earlier this year, Osaka's return to Flushing Meadows did not go to plan, as she wordlessly left the court after uncharacteristically losing her cool in the second set tiebreak.

The third seed whacked her racquet and then flung it onto the court twice in frustration as Fernandez scored five straight points in the tiebreak, in a series of superb play.

Osaka not receive a warning or a code violation and left the court in between sets.

Her troubles continued as the 18-year-old Canadian broke her serve to kick off the third set, and Osaka hit a ball into the stands in the second game, prompting a warning from the chair umpire.

In the ninth game Osaka rushed through her serves, not even waiting for the crowd to quiet down, as she was unable to create a single break point opportunity in the final set.

Fernandez, who fired off 28 winners across the three sets, said in a televised interview that she worked at "just finding the solutions."

"She's a great server, she's been hitting aces left, right and centre," she said, three days shy of her 19th birthday. "As I was getting closer to the baseline I was like 'Oh, this is where I should be.'"

A fan favourite in virtually any tennis venue, Osaka has struggled with uneven play since she withdrew from Roland Garros earlier this year amid a public row with tournament officials over media obligations, which she said had a negative impact on her mental health.