Williams, the defending champion, is coming off a hard-court tournament victory at Dubai on Sunday. She seemed to have few problems beating the jet-lag and making the switch to the slippery clay.
"It was a really good first match," Williams said. "I was just trying to get my rhythm on the clay and make the transition."
Williams has never won the French Open, the only Grand Slam event on clay. But she reached the 2002 final and sounded positive about still having a chance.
"I think inherently right now I am a lot more patient," she said. "So when I see that open court I know that it's not necessarily a winner on clay -- so it doesn't look so tempting. I feel smarter, actually.
"I've won almost every [clay-court] tournament I've played and I got to the finals of the French," she added. "I just haven't had that title yet. Some people say 'she's not that good on clay,' but I don't feel that way. At the end of the day it's about how I feel on the court. I'm good on it."
In other women's first round matches, third-seeded Gisela Dulko of Argentina defeated Lucie Hradecka of the Czech Republic 6-1, 2-6, 6-1 and No. 5 Carla Suarez Navarro of Spain beat Hungary's Greta Arn of Hungary 6-0, 6-0.
On the men's side, the top four seeded players all advanced.
No. 1-seeded Fernando Verdasco of Spain rallied from a set down to defeat Italy's Fabio Fognini 2-6, 6-4, 6-0. No. 2 Fernando Gonzalez of Chile held on to beat Sam Querrey of United States 6-4, 3-6, 7-6 (2).
Verdasco, the No. 10-ranked player, saved all six break points he faced in the second set before dominating the final set.
Verdasco defeated Andy Roddick in the SAP Open final 10 days ago in San Jose, California, but lost in the first round last week in Memphis.