Garbine Muguruza rallied from a set down to reach the second round of the U.S. Open after Elise Mertens threatened to pull off a big upset, while Angelique Kerber had no such trouble on Day 1.
Muguruza, ranked third in the world, came into the final major of the year with only one singles victory to her name at Flushing Meadows and the French Open champion was in danger of making a first-round exit before battling back to win 2-6, 6-0, 6-3 on Monday.
Mertens, of Belgium, was playing in the main draw of a grand slam singles tournament for the first time, but was unable to take advantage of an unconvincing display from the third seed from Spain.