(CNN) -- Serena Williams booked a place in the quarterfinals of the U.S. Open on Monday with a flawless 6-0 6-0 victory over Andrea Hlavackova at the Arthur Ashe Stadium.
The 30-year-old who is seeking a fourth singles title at Flushing Meadows needed just 57 minutes on court to see off the world No. 82 from the Czech Republic.
"Andrea played really well. She never gave up. She's such a great fighter. But I played really well today, I tried to stay relaxed and do what I do. I knew she would be a dangerous opponent," Williams said.
Ana Ivanovic awaits Williams in the last eight after she defeated Bulgaria's Tsvetana Pironkova 6-0 6-4 in 71 minutes.
The Serb appearance in the last eight is her best performance at the U.S. Open and the first time she has reached any Grand Slam quarterfinal in four years.
"I hardly made any mistakes in the first set but she is a tough opponent and I knew she would come back in the second set," Ivanovic said.
"It's amazing to be in my first quarter-final at the US Open."
10th seed Sara Errani is also through to the last eight after a hard fought straight sets (7-6 6-3) victory over Germany's Angelique Kerber.
The Italian, who was runner-up at the French Open in June, will face her compatriot Roberta Vinci.
The 19th seed overcame number two seed Agnieszka Radwanska from Poland 6-1 6-4.