The Latest: Extreme heat policy in effect at US Open

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              Madison Keys reacts after defeating Dominika Cibulkova, of Slovakia, during the fourth round of the U.S. Open tennis tournament, Monday, Sept. 3, 2018, in New York. (AP Photo/Carolyn Kaster)
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NEW YORK (AP) — The Latest on the U.S. Open tennis tournament (all times local):

12:55 a.m.

Roger Federer has been stunned in the U.S. Open’s fourth round by 55th-ranked John Millman of Australia 3-6, 7-5, 7-6 (7), 7-6 (3).

It’s the first time in Federer’s career that he has lost to a man ranked outside the top 50 at Flushing Meadows.

The 20-time Grand Slam champion double-faulted 10 times, including twice in a row during the final tiebreaker.

Federer certainly had his chances to take control of the match, including two set points at 5-4, 40-15 in the second. He also blew a set point in the third.