PARIS — Serena Williams beat Iveta Benesova of the Czech Republic 6-1, 6-4 Wednesday to advance to the second round of the Open GDF Suez.
The top-ranked American became ill after winning the Australian Open and wasn't able to practice until Monday.
"I was in bed. I was really sick until I came here," Williams said. "It was like a week. I couldn't do anything."
Jelena Jankovic of Serbia, Patty Schnyder of Switzerland and Amelie Mauresmo of France also advanced at the indoor hard court tournament.
Williams saved two break points on her first service game before winning six straight to take the first set on an unforced error from Benesova.
"I wasn't great. I was so glad to win," Williams said. "As the tournament goes on, I'll do a little better."
The 34th-ranked Czech fought back in the second set, but Williams won the match on Benesova's serve with a backhand winner down the line.
"She raised her game and I made some key errors on some key points (in the second set)," said Williams, who will next play Croatian qualifier Karolina Sprem.
Williams, who recently bought an apartment in Paris, playfully answered some questions from the local press in French.
"I feel so-so. I'm tired right now. I'd like to sleep," she said in French.
Jankovic defeated Francesca Schiavone of Italy 7-5, 7-6 (2), winning the first set on a double-fault.
"It's a relief to finish in two sets," the third-ranked Serb said. "After the first set and 3-0, I really lost my energy and my game went down. I let my opponent come back into the match. Until then, I was completely in control.
"I'm lucky that I was somehow able to get through the second set," Jankovic added. "As a top player, when you have everything under control, you have to finish your opponent off."
Schnyder beat Alona Bondarenko of Ukraine 6-4, 7-6 (3), and Mauresmo avenged her Fed Cup loss last weekend to Sara Errani by routing the Italian 6-2, 6-0.
In the second round, Jankovic will face Li Na of China and Schnyder will meet French wild card Nathalie Dechy.
French qualifier Emilie Loit beat Kaia Kanepi of Estonia 2-6, 6-3, 6-1 to become the first player to move into the quarterfinals.