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.

Madison Keys suffered one of the biggest upsets of the 2025 season on Monday at the US Open, losing to Renata Zarazua.

Australian Open champion Madison Keys has been undone by 89 unforced errors during a 6-7 (10), 7-6 (3), 7-5 loss to Mexico’s Renata Zarazua in the first round of the U.S.