(CNN)In a stunning result, US Open defending champion Naomi Osaka lost her third-round match to Canada's Leylah Fernandez in three sets, as the world No. 3 and four-time major champion uncharacteristically showed signs of frustration on the court and expressed doubts after the match.
Naomi Osaka considering taking another break from tennis after US Open loss
"I honestly don't know when I'm going to play my next tennis match," Osaka said through tears in a press conference. "I think I'm going to take a break from playing for a while."
Osaka, who was leading by a set, broke Fernandez for a 6-5 lead in the second set. But when serving for the match, Osaka couldn't close it out. During the tiebreak, Osaka slammed her racquet to the court.
Fernandez, 18, would win the tiebreak to force a final set, and then the world No. 73 broke Osaka to open the third. Not long after that, Osaka hit a ball into the crowd and was hit with a code violation for ball abuse.
Fernandez went on to win the match 5-7, 7-6(2), 6-4.
The Canadian, who turns 19 on Monday, will next face No. 16 seed and three-time major champion Angelique Kerber of Germany.
Fernandez -- who played a brilliant match -- gave credit to the crowd in her on-court interview, as the Canadian had tremendous support from those in attendance.