Sixth seed Serena Williams has battled sluggish conditions to defeat fellow American Kristie Ahn 7-6 (7-2) 6-0 to open her campaign at the French Open.

Playing against an opponent she defeated at the same stage at the US Open less than a month ago, Williams found herself trailing twice in the opening set at the Court Philippe Chatrier but rallied each time to force a tiebreaker.

Williams, who has won three of her 23 grand slam singles titles at Roland Garros, raised her level in the tiebreaker and did not look back from there, handing the 102nd-ranked Ahn a bagel in the second set.

The 39-year-old had to dig deep to find a way to win points in the cold and heavy conditions and needed five match points to seal the victory and set up a second round meeting against Tsvetana Pironkova, who beat Andrea Petkovic 6-3 6-3.

Earlier on Monday, seventh seed Petra Kvitova eased through to the second round after she completed a 6-3 7-5 win against France’s Oceane Dodin under the roof of Court Philippe Chatrier.

“It was really a tough one,” said Kvitova, who plays Jasmine Paolini in the next phase after the Italian dismissed Spain’s Anna Bolsova 6-4, 6-3.

Dutch fifth seed Kiki Bertens survived a scare in her tie with Ukraine’s Katarina Zavatska as Bertens battled from a set down to prevail 2-6 6-2 6-0.

Ukrainian third seed Elina Svitolina is also through after she eliminated Varvara Gravcheva of Russia 7-6 (7-2) 6-4 and will play Mexican qualifier Renata Zarazua next.