By Larry Fine

NEW YORK (Reuters) - Sixth-seeded Venus Williams stayed on track for a possible semi-finals clash with sister Serena by sprinting past German Julia Goerges to reach the third round of the U.S. Open on Thursday.

Williams, 36, relied on her big serve when pressed in posting a 6-2 6-3 victory under the roof at Arthur Ashe Stadium, turning away four of five break points held by the 64th-ranked Goerges.

Williams, the U.S. Open winner of 2000 and 2001, was runner-up to top seed Martina Hingis as an unseeded player in the inaugural year of Ashe Stadium and 19 years later finished the first U.S. Open day session played entirely under a roof.

"1997 was a long time ago," Williams said on court after her victory. "I'm so grateful to be here still playing, still winning matches and I can't wait for the next round."

The elder Williams sister will next play either 26th seed Laura Siegemund of Germany or unseeded American Nicole Gibbs.

(Editing by Mark Lamport-Stokes)