Defending champion Williams cruises into third round

Serena Williams took another emphatic step in defense of her U.S. Open title by crushing Galina Voskoboeva of Kazakhstan 6-3, 6-0 on Thursday to reach the third round of the year's final Grand Slam.

The top-seeded American took a short while to get accustomed to breezy conditions on Arthur Ashe Stadium court before winning 10 of the last 11 games in a 69-minute rout.

Williams, 31, has dropped just four games in four sets at Flushing Meadows this year, slamming the door on the 77th-ranked Voskoboeva by limiting her to nine points in the second set.

The world number one will next meet Voskoboeva's compatriot Yaroslava Shvedova, a 6-2, 6-3 winner against Patricia Mayr-Achleitner of Austria.

Sara Errani became the highest seed to be knocked out of this year's U.S. Open when she suffered a surprise 6-3, 6-1 loss to Flavia Pennetta on Thursday.

Errani, seeded fourth for the women's singles, was sent packing after just 71 minutes by her fellow Italian in a second round match at Arthur Ashe Stadium.

A semi-finalist at Flushing Meadows last year, Errani was looming as a contender this year and appeared to be in great form after doling out a rare double-bagel win in her opening match against Australia's Olivia Rogowska in under an hour.

Errani will now focus her attention on the doubles where she and her countrywoman Roberta Vinci will defend the title they won last year.

Vinci fared better in her second round singles match on Thursday with the 10th seed defeating Lucie Safarova 4-6, 6-1, 6-2.