Tearful Naomi Osaka questions future after US Open loss to Leylah Fernandez

• Osaka says she will take a break for a while' after stunning loss
• Fernandez earns career-best 5-7, 6-7 (2), 6-4 win in third round

Naomi Osaka's defense of her US Open championship is in tatters and her immediate future on the women's professional tennis tour in doubt after a shocking third-round defeat to the unseeded Leylah Annie Fernandez, a Canadian teenager ranked 74th in the world.

The third-seeded Osaka, a four-time major champion and the best hard-court player in the world by some distance, lost her composure while serving for the match, came apart during the ensuing tiebreaker and couldn't right the ship in the third during a 5-7, 6-7 (2), 6-4 loss in 2hr 4min on Friday night.