NEW YORK - Two-time U.S. Open champion Naomi Osaka exited the tournament in the fourth round Monday with a 6-1, 6-4 loss to No. 2 seed Elena Rybakina of Kazakhstan.

Japan's former world No. 1 gave up an early break on her second service game and from there could not gain an upper hand over the in-form Rybakina, who wrapped up the contest in 66 minutes.

Related coverage: