PARIS -- Rattled by the stress of a French Open marathon, American Ashley Harkleroad settled her nerves, choked back tears and earned a milestone victory.

The 18-year-old native of Roseville, Ga., advanced to the third round of a Grand Slam event for the first time Wednesday, beating No. 9-seeded Daniela Hantuchova 7-6 (2), 4-6, 9-7.

Harkleroad won despite blowing a 5-1 lead in the third set and losing five consecutive games. The letdown left her on the verge of defeat, and her eyes glistened with emotion.

"I was so tight and wanting it so bad, I guess,'' she said. "I said, 'OK, Ashley, you're not going to lose this. You're going to fight.' I tried to breathe and relax.''

She did, and after three hours, eight minutes of tennis, Harkleroad earned the first match point. When Hantuchova sailed her final shot wide, Harkleroad squealed, dropped her racket and sprinted to the stands for a celebratory hug from her agent.

Defending champion Serena Williams won with much less drama. She overcame 32 unforced errors and extended her Grand Slam winning streak to 30 matches, beating Marie-Gaianeh Mikaelian 6-3, 6-2.

Harkleroad also beat Hantuchova at Charleston, S.C., in April, but this win came on a much bigger stage. Hantuchova, who had reached the quarterfinals in the last three major events, contributed to her defeat with 106 unforced errors.

"Sometimes I was going too much for it and doing too many mistakes,'' Hantuchova said. "In the end, it was just a couple of points that decided the match.''

She was exactly right: The slender Slovakian won 131 points, Harkleroad 133.

American Laura Granville, seeded 31st, beat 1997 champion Iva Majoli 6-1, 6-2. No. 21 Lisa Raymond lost to Flavia Pennetta 6-3, 7-6 (3), and No. 23 Anna Pistolesi lost to Magui Serna 6-4, 3-6, 6-3.

Clarisa Fernandez, a semifinalist last year, was beaten by Barbara Schett 6-4, 5-7, 6-1. Schett will next play Williams.

Other second-round winners included No. 4 Justine Henin-Hardenne, No. 8 Chanda Rubin, No. 14 Eleni Daniilidou, No. 16 Ai Sugiyama, No. 18 Meghann Shaughnessy and No. 19 Patty Schnyder.

Harkleroad, a runner-up in the juniors at Roland Garros last year, is ranked 52nd -- tops among U.S. teenagers. She has drawn comparisons to Anna Kournikova, and her matchup with the equally photogenic Hantuchova attracted a crowd of cheering youngsters who made Court 1 sound like a schoolyard playground.

The two blond opponents appeared almost identical because they wore matching powder-blue outfits -- to their dismay.

"It's a nice color,'' Hantuchova said with a rueful smile. "But I don't think it's good when both of us are wearing the same thing.''

Despite some sloppy shotmaking, the match was filled with entertaining, scrambling exchanges. Through a series of momentum swings, Harkleroad showed impressive persistence.

"I've always been very feisty and a fighter,'' she said. "I don't know where it came from. It's just me.''

Harkleroad began rushing her shots in the third set to fall behind 6-5. She recovered with help from the erratic Hantuchova, who committed eight unforced errors to lose eight of the next nine points.

Harkleroad held serve for an 8-7 lead, and errors by Hantuchova on the final three points gave the American the victory.

Henin-Hardenne beat Jelena Kostanic 6-2, 6-2, while Rubin defeated Cara Black 7-6 (6), 6-3.