Ivanovic has never got beyond the third round in New York

Justine Henin, Jelena Jankovic and Serena Williams also made progress.

Ivanovic, 19, trailed Aravane Rezai 3-1 in the opening set but stormed back to win 6-3 6-1 and book a meeting with Russian Vera Dushevina.

"It's no secret that my half of the draw is harder," said Ivanovic. "My first goal is to make the second week."

Twice champion Venus Williams beat Romanian Ioana Raluca Olaru 6-4 6-2.

"I think I missed a few shots that were easy, but ultimately, it's important to get to the next round," said Williams, who hit six double faults.

In a Grand Slam you have to be strong Justine Henin

"I always feel like my game will be there. I'm not stressed out on a few shots, feel a little wiser. It was good today.

"I definitely feel like I'm on a roll. I feel like when I need the points I get them. I'm playing very strong. Everything is going well."

Serena Williams was below her best in beating Italy's Maria Elena Camerin 7-5 6-2 in the first of Wednesday's night matches.

The former champion let a 4-1 lead slip in the opening set before edging it and, despite taking an early lead in the second, rarely looked totally comfortable.

But Williams insisted: "I feel a lot better than I did in the first round, that's for sure. I've still got to get it together though.

"She played a great game and all credit to her, but I'm definitely getting a lot stronger and feeling a lot better and I'm happy to be out here."

Top seed Justine Henin overcame a stern first-set challenge from Tsvetana Pironkova before easing into the third round.

Bulgarian Pironkova stayed with her the world number one until 4-4 before Henin reeled off eight straight games to win 6-4 6-0.

606: DEBATE Your thoughts on day three

"In a Grand Slam you have to be strong," said the Belgian. "It's tough. It's long. You need to be consistent for two weeks.

"I'm happy the way I won my last two matches, just go step by step and try to build my confidence day by day."

Henin will face 19-year-old Russian Ekaterina Makarova in the third round.

Makarova, playing in her first Grand Slam tournament, caused a minor upset when she beat 28th seed Ai Sugiyama of Japan 6-4 4-6 6-2.

Third seed Jelena Jankovic reached the third round with a 6-2 6-2 win over Olga Govortsova of Belarus, and goes on to face Alize Cornet of France.

"It was a lot better than my first round," said Jankovic. "But I feel also a little bit slow, especially on the returns."

Sybille Bammer, the 19th seed, was another early winner on day three, beating American Meghann Shaughnessy 6-4 6-3.