Britain's Sonay Kartal suffered a first-round defeat to Caroline Garcia at the Cincinnati Open.
The 23-year-old was beaten 7-5 4-6 3-6 by her French opponent, who won the 2022 tournament.
Garcia, the former world number four, will now face Karolina Muchova after the 31-year-old's first victory since 19 March, having announced in May she would retire later this year.
Kartal's loss followed first-round exits for fellow Britons Katie Boulter and Jacob Fearnley.
Boulter, 29, was beaten 6-0 7-5 by Serbia's Olga Danilovic, who will now face Emma Raducanu - who recently dethroned Boulter as British women's number one - in the second round.