Britain's Heather Watson suffered a seventh successive defeat as she lost to American Taylor Townsend in the first round of the Volvo Car Open.
World number 71 Watson, who is ranked 47 places above 21-year-old Townsend, lost 6-3 6-4 in Charleston.
Watson, 25, from Guernsey, has not won since reaching the semi-finals of the Hobart International in January.
Briton Naomi Broady, 28, beat Canada's Carol Zhao 6-3 6-7 (5-7) 6-2 to reach round two of the Monterrey Open.