Defending champion Angelique Kerber battled her nerves and blew a match point in the second set before finally overcoming Lesia Tsurenko 6-2, 5-7, 6-2 to reach the second round.
Top seeds Novak Djokovic and Serena Williams face challenging early tests at the US Open following Friday's draws for the year's last Grand Slam starting on Monday.
Top seed Novak Djokovic has been starved of competitive action at the US Open but on Sunday the World No 1 feasted on unseeded Briton Kyle Edmund in a 6-2, 6-1, 6-4 romp that put him into the quarter-finals.
Wimbledon's genteel surrounds resembled Saturday night on a casualty ward as injuries saw seven players withdraw or retire and third seed Maria Sharapova stumble to a shock second-round defeat on Wednesday.
Images from the men's singles quarter-finals at Wimbledon on Wednesday.
Fourth seed Rafael Nadal showed he is healthy and ready to challenge for a third US Open title as he rolled into the last 16 at Flushing Meadows on Friday with a fist-pumping 6-1, 6-4, 6-2 win over Russian Andrey Kuznetsov.
Photos from Day 5 action at the Western & Southern Open at Cincinnati on Thursday.
It was a day of surprises at Flushing Meadows in New York as seeded players were knocked out one after the other on Friday.
