Pretty much from the get-go at the U.S. Open on Monday, Madison Keys could tell she wasn’t hitting the ball well or feeling very much at all like the self-confident player who claimed her first Grand Slam title at the Australian Open in January.

NEW YORK — Australian Open champion Madison Keys is out of the U.S. Open in the first round. Renata Zarazúa, the world No. 82 from Mexico, came from a set and 3-0 down to stun the No. 6 seed 6-7 (10), 7-6 (3), 7-5 in bright sunlight on Arthur Ashe Stadium. Zarazúa also became the first Mexican woman to ever beat a top-10 opponent at the U.S. Open.

Australian Open champion Madison Keys was undone by 89 unforced errors and was upset in the first round of the U.S. Open by Renata Zarazua of Mexico.