It was her first Grand Slam back after withdrawing from the French Open and Wimbledon due to mental health issues.
Meanwhile, British teenager Emma Raducanu aims to continue
her impressive debut at the US Open tennis later.
The world number 150 faces Spain's Sara Sorribes Tormo in the
third round at Flushing Meadows.
Raducanu reached the second week of Wimbledon earlier this
year.
She says that experience is helping her not to get carried away.