Top-seeded Nadia Petrova of Russia moved into the Amelia Island Tournament semi-finals, while second seed Patty Schnyder was eliminated on Friday.
Petrova, who has won 21 tour matches this year, needed just one hour and eight minutes to beat Spain's Virginia Ruano Pascual 6-3, 6-0. Switzerland's Schnyder was beaten 6-3, 6-1 by fifth-seeded Svetlana Kuznetsova of Russia.
After battling through a tough first set, Petrova lost just nine points and in the second set and won the final nine games to clinch victory.
"I was prepared for a long match," Petrova told reporters. "As soon as I had an opportunity I was trying to make the points shorter and save energy. I'm happy with the consistency of my game."
Kuznetsova had just as easy a time against Schnyder after splitting the first four games of the first set, taking just under an hour to finish off the match.
She drilled 26 winners and broke Schnyder five times.
"I played well," Kuznetsova told reporters.
"The first set, I was just trying to get comfortable with her game, then I worked to beat her. I didn't have too many unforced errors and I still went for a few hard shots, so I'm getting better."
It was Kuznetzova's third straight win over a top 10 player.
"She did everything so well," Schnyder said.
"She was a complete player today, all over the court."
In other quarter-final play on Friday, Italy's Francesca Schiavone crushed Germany's Anna-Lena Groenefeld 6-2, 6-3.
Schiavone meets Kuznetsova in the semi-finals on Saturday. The Russian has won three of their previous four meetings.
Lucie Safarova earned a semi-final clash with Petrova by dominating American Jill Craybas 6-2, 6-2.
It will be the first match between Petrova and Safarova, and Safarova's first semi-final appearance.
(Writing by Roger Lajoie in Toronto)