“For the first time in a while, my nerves really got the better of me, and it kind of became a little bit paralyzing,” Keys said after the match. “I felt like I was just slow. I wasn’t seeing things the way that I wanted to, which I feel like resulted in a lot of bad decisions and lazy footwork.”

Madison Keys admitted nerves "paralyzed" her in New York as she suffered an unexpected US Open first-round defeat to unseeded 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. Open

Day two of the US Open delivered the tournament’s first big stunner. Renata Zarazúa of Mexico defeated No. 6 seed Madison Keys 6-7(10), 7-6(3), 7-5 in a major first-round upset at Arthur Ashe Stadium Monday afternoon.