NEW YORK (Reuters) - Serena Williams took another emphatic step in defence 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.

(Reporting by Larry Fine; Editing by Frank Pingue)