India's Sania Mirza scored a streaky win over Emma Laine of Finland to set up a quarterfinal clash with top seed Patty Schnyder at the Cincinnati Open.
Sania, seeded ninth, advanced with a 6-1, 0-6, 6-1 victory over Laine in the second round.
Top seed and defending champion Patty Schnyder of Switzerland crushed American Abigail Spears 6-1, 6-0 on Wednesday to storm into the quarter-finals.
After needing three sets and a tie-break to see off Lilia Osterloh in her opening match on Monday, Schnyder, the world number eight, needed just 53 minutes to dispose of the qualifier.
Schnyder, who has not won a title since winning in Cincinnati a year, raced to a 3-0 lead before allowing Spears a brief moment of hope claiming her only game at 3-1.
After that the veteran Swiss swept through the next nine games to keep her title defence on track.
"I knew I had to work on some things after the first match, I didn't expect such a big difference after just one day," Schnyder told reporters.
Fourth seed Katarina Srebotnik of Slovenia tamed China's Meng Yuan 7-6 (7-3), 6-1 to reach the last eight while American Amy Frazier rolled to a 6-3, 6-1 win over eighth-seeded Argentine Gisela Dulko
And Russia's Vera Zvonareva swept past French seventh seed Tatiana Golovin 6-3, 6-0 in the day's only first-round contest.