Serena Williams has recovered from a sluggish start to beat Bulgaria's Tsvetana Pironkova 5-7 6-1 6-1 in a rain-hit French Open first-round match.

The Australian Open champion, who won the Paris tournament in 2002 but has missed it for the last two years, struggled at first against an opponent ranked a modest 91st in the world. Making clumsy errors, Williams, seeded eighth, dropped serve straight away and found herself 5-2 down after just 28 minutes.

The American then survived a set point but Pironkova later earned three more, while leading 5-4, wasting all of them.

The 19-year-old Pironkova, who beat Williams's sister Venus in the first round of last year's Australian Open, did not give up and broke her opponent again to lead 6-5.

The match was then stopped for nearly six hours because of rain. When it resumed, Pironkova won her service game to love to wrap up the set.

"The conditions were difficult," Williams said. "The rain really slows the court down.

"I was already coming back when there was the break and there's no way I wouldn't have gone to at least three sets," she added.

The 25-year-old Williams then turned on the power, taking the second set 6-1 in 30 minutes with a service winner on set point.

"I'm a fighter", she said. "I've never lost in the first round of a Grand Slam and I didn't want that to change.

"I was also feelling that if I went down, there was a 99.9 per cent chance she would lose in the next round. That helped me keep fighting. I couldn't lose on the Sunday, no way."

The decisive set was a formality for Williams, who earned two match points with a blistering return winner.

She hit a return long on the first but on the second Pironkova fired a backhand wide to bow out after two hours 12 minutes of play.

"I was feeling better in that third set, sliding better, playing the way I want to be playing on clay," said Williams, who goes on to meet Frenchwoman Virginie Razzano or Venezuela's Milagros Sequera.

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