Williams had 13 of her 19 unforced errors in the opening set when the 76th-ranked Camerin traded crisp groundstrokes with the eighth-seeded American.

• Images from day 3 | Coverage

But with the score tied at 5-5, Williams found her stride and won eight of the final 10 games.

"I feel like I played better than I did in my first match," Williams said. "But I'm still trying to get it to come together."

In her first round match, an error-prone Williams defeated Germany's [ Images ] Angelique Kerber 6-3 7-5.

The two-times U.S. Open champion had not played in a tournament since losing to Justine Henin [ Images ] in the quarter-finals of Wimbledon [ Images ] last month.

In the third round Williams will play Russian Vera Zvonareva [ Images ], who knocked out Maria Sharapova [ Images ] from the Australian Open [ Images ] in the round of 16 earlier this year.