Lesia Tsurenko has admitted that she made changes to her serve ahead of her first-round US Open win over sixth seed Lucie Safarova.
The Ukrainian lost to the Czech player in the Connecticut Open just a week before her 6-4 6-1 victory over the French Open finalist at Flushing Meadows.
The 26-year-old told the WTA website: "I talked with my coach about what to change. I changed the serve a little bit, made it a more active movement. I received pretty back because she was a left. This time I was playing at the back more."
Tsurenko will face America's Varvara Lepchenko in the second round.