Shelby Rogers booked her spot in the MUSC Health Women's Open quarter-finals, but fellow seeds Ajla Tomljanovic and Lauren Davis crashed out.
Following her third-round appearance at the Volvo Car Open, Charleston native Rogers moved through to the quarters of her second hometown tournament in as many weeks after easing past qualifier Claire Liu 6-2 6-2.
"I think I was due for a couple of tame matches," said third seed Rogers, who lost to world number one Ash Barty at last week's Volvo Car Open. "I've had quite a few mental battles over the last couple of months, so it's been nice to just take care of business in straight sets, get in and get out."
Next up for Rogers at the WTA 250 event is in-form Montenegrin opponent Danka Kovinic, who upstaged seventh seed Davis 6-1 1-6 6-3 on Wednesday.
Australian sixth seed Tomljanovic was swept aside by teenager Clara Tauson 6-1 6-4, while Nao Hibino beat Francesca Di Lorenzo 6-4 6-3.