Keothavong will now face Portugal's Larcherde
Anne Keothavong reached the second round of the RMK Championships with a 3-6 6-3 6-1 win over Italy's Maria Elena Camerin in Memphis.
The fourth seed now faces highly-rated 16-year-old Michelle Larcher de Brito of Portugal, the world number 124.
Fellow Briton Melanie South lost 6-2 6-2 to third seed Lucie Safarova.
In the men's event, Britain's Jamie Murray and Serbian partner Dusan Vemic defeated Max Mirnyi and Robert Kendrick 6-3 6-2 in the doubles first round.
Murray and Mirnyi ended their doubles partnership in September after teaming up at the start of 2008.
Murray has struggled for form this season and Monday's win was only his second of 2009.