Keys reached the US Open final in 2017 but lost to Sloane Stephens
Australian Open champion Madison Keys suffered a shock defeat by Mexico's Renata Zarazua in the first round of the US Open, paying the price for an error-strewn performance.
The sixth seed's first home major as a Grand Slam champion did not go to plan as she made 89 unforced errors in a 6-7 (10-12) 7-6 (7-3) 7-5 defeat.
Keys made 37 unforced errors in the first set alone but managed to take it on a tie-break after world number 82 Zarazua spurned five set points.
The match looked there for the taking for Keys as she breezed to a 3-0 lead in the next set, but the 2017 runner-up in New York then lost four consecutive games.
