KEY BISCAYNE, Fla. — Venus Williams became the first player to reach the quarterfinals at the Sony Ericsson Open, defeating 17-year-old Caroline Wozniacki 6-3, 6-3 today.

Williams is a three-time champion, with her most recent Key Biscayne title coming in 2001.

A superior serve and return helped Williams defeat Wozniacki, a Dane who has won 14 matches this year to climb to a career-best 43rd in the rankings. Williams lost only six points on her first serve and repeatedly slammed Wozniacki's serve for winners.

"I played some good tennis and aggressive when I needed to, and a lot of really good service games," Williams said.

Seeded sixth, Williams finished with 23 winners. She's 10-4 this year and trying for her first 2008 title.

"I definitely feel like I'm playing well," she said. "I'm always trying to take it to another level, regardless. If I'm playing on cloud nine, I'm trying to get to cloud 10, and actually cloud 11."