Dominant Serena reaches U.S. Open quarters

Three-time champion Serena Williams was an easy fourth-round winner Monday at the U.S. Open.

The fourth-seeded former world No. 1 Williams double-bageled helpless Czech Andrea Hlavackova, 6-0, 6-0, in a mere 56 minutes at Ashe Stadium on Labor Day in the United States.

Williams was last year's U.S. Open runner-up to Aussie Samantha Stosur.

The 30-year-old 14-time Grand Slam champion Williams captured Wimbledon in July and secured a singles gold medal at the London Olympic Games, also at the All England Club, last month.

The 14-time Grand Slam champion Williams' quarterfinal opponent will be fellow former No. 1 Ana Ivanovic of Serbia. The 12th-seeded former French Open champion Ivanovic handled Bulgarian Tsvetana Pironkova 6-0, 6-4 on the hardcourts at the USTA Billie Jean King National Tennis Center.

The 24-year-old Ivanovic will now appear in her first major quarterfinal since capturing the French Open more than four years ago.

Ivanovic is 0-3 lifetime against Williams, including a pair of losses at the U.S. Open. The American beat the Serb in the round of 16 here a year ago and also bested Ivanovic in the third round in Flushing back in 2006.

Surprise French Open runner-up Sara Errani is now a surprise first-time U.S. Open quarterfinalist after ousting sixth-seeded German Angelique Kerber 7-6 (7-5), 6-3 at Armstrong Stadium on Day 8.

The left-handed Kerber was a U.S. Open semifinalist last year and reached the Wimbledon semis in July.

The 25-year-old Errani has now reached at least the quarterfinals at three of the four Grand Slam events in 2012.