Maria Sharapova proved too strong for India's Sania Mirza as she prevailed 6-2 6-1 in their fourth-round encounter at the US Open on Sunday.
Mirza matched Sharapova for power off the ground but her serve let her down.
Despite the scoreline Sharapova had to hit top gear to reach the last eight - where she faces fellow Russian Nadia Petrova - for the first time.
"I'm playing pretty well," said Sharapova. "I know it's going to get tougher and tougher from here."
Mirza, who made 23 unforced errors, insisted she did not regret her tactics of trying to outhit Sharapova from the baseline.
"I'm going to win matches by hitting winners," said the 18-year-old.
"I enjoy hitting the ball as hard as I can and I enjoy taking risks. I enjoyed every minute out there."
She added: "This is my career highlight. Getting to the fourth round in the US Open in my first year in the US Open and first year on the tour."
Kim Clijsters gave Venezuela's Maria Vento-Kabchi a 6-1 6-0 mauling in the opening match of the night session.
The fourth seed struck 20 winners as she booked a quarter-final meeting with Venus Williams in just 42 minutes.
Petrova, the ninth seed, became the first women to reach the quarter-finals with a 7-6 (7-4) 7-5 win over Nicole Vaidisova.
Petrova hit back from a 2-5 deficit in the first set against her 16-year-old opponent from the Czech Republic to win in one hour 45 minutes.
She is through to the quarter-finals for the second year in a row.