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.