TALLAHASSEE, Fla. (AP) _ Defending champion Keri Phebus of UCLA advanced to the quarterfinals of the NCAA Division I Women's Tennis Championships on Thursday with a straight set victory.

Phebus defeated Brigham Young's Eline Chiew 6-3, 6-1 in the second round, then beat Jean Okada of UC-Santa Barbara 6-2, 6-1.

Clemson freshman Sophie Woorons, the Atlantic Coast Conference Player of the Year, registered the biggest upset of the day, beating third-seeded Vicky Maes of Arizona 6-2, 3-6, 7-5 in a match that lasted 2 hours, 38 minutes.

Woorons, a French native, will meet Arizona State's Reka Cseresnyes in the quarterfinals Friday. Cseresnyes upset eighth-seeded Melissa Zimpfer of Wisconsin 6-2, 6-4.

Top-seeded Kylie Hunt of Kansas cruised into the quarterfinals with a 6-4, 6-2 win over Georgia's Anne Chauzu, and a 7-5, 6-1 win over UCLA's Paige Yaroshuk.

Hunt faces Florida's Divya Merchant in the quarterfinals. Merchant defeated teammate Dawn Buth, the seventh seed, 0-6, 7-5, 6-1.

It was Buth's sixth straight three-set match since the team championships earlier in the week, and her first loss. Merchant has defeated Buth two of three times in individual tournament competition this season.

Florida's Jill Craybas, a singles semifinalist last year, has lost just seven games in advancing to the quarterfinals. Craybas, seeded fourth, beat Alabama-Birmingham's Gulberk Gultekin 6-2, 6-3, and Notre Dame's Jennifer Hall 6-1, 6-1.

Duke's fifth-seeded Vanessa Webb, who meets Craybas in the quarterfinals, advanced with a 6-4, 6-0 win over Stanford's Sandra De Silva, and a 6-4, 6-1 win over Mississippi's Agnes Muzamel.

Sixth-seeded Ania Bleszynski of Stanford eliminated California's Pam Enkoji 6-2, 6-0, then beat Florida State's Lori Sowell 7-5, 6-3.

Bleszynski will meet Phebus in the quarterfinals Friday.