NEW YORK - Japan's former world No. 1 Naomi Osaka reached the fourth round of the U.S. Open on Saturday after battling past Elise Mertens of Belgium 6-3, 3-6, 7-5.

Osaka, the 13th seed and 2018 and 2020 champion, was a break down in the third set in New York but found a way back to overcome the 23rd-seeded Mertens to make the last 16 for the second straight year.

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