Serena Williams won 10 of the last 12 games to defeat Marina Erakovic 6-2, 6-2 and move into the quarterfinals at the Family Circle Cup on Thursday.
The fifth-seeded Williams will meet either Sabine Lisicki or Yaraslava Shedova on Friday for a spot in the semifinals, where's Serena's sister Venus could be waiting.
Venus Williams faces Anastasia Rodionova in a later third-round match.
Serena Williams got her game going at 2-2 in the first set after she missed several chances to break Erakovic's serve before losing that game. Williams won the next four games to close out the set.
Erakovic double-faulted on match point as Williams pumped her fist in triumph.
In another third-round match, third seeded Marion Bartoli fell in three sets to No. 14 Polona Hercog.