PARIS - Wimbledon champion Petra Kvitova powered into the last 16 at the French Open on Saturday after early round struggles at Roland Garros, while Sloane Stephens revived flagging American hopes. Kvitova, the fourth seed from the Czech Republic, finally found her form to outplay Romanian Irina-Camelia Begu 6-3, 6-2 in just 58 minutes, taking the last five games at a canter.

That was in stark contrast to her first two rounds that saw her grind out six sets and spend just four minutes short of five hours on the court. "I think it was for sure the best match which I played here so far, so I'm really glad for it," Kvitova said. "I'm glad that I didn't forget many things from my game and it's still there. "Next up for Kvitova, who also won Wimbledon in 2011, but who has only managed a single semi-final in Paris in 2012, will be a fourth round tie against Timea Bacsinszky of Switzerland who upset 16th seeded American Madison Keys 6-4, 6-2. Stephens, clawing her way back up the world rankings after a bad wrist injury sidelined her late last year, saw off Bulgaria's Tsevtana Pironkova 6-4, 6-1, winning eight of the last nine games to clinch the victory.

Her reward for that is likely to be a fourth round clash with top seed and compatriot Serena Williams. Also through to the last 16 in early play was Italian Sara Errani, losing finalist in 2012, who gained revenge on Andrea Petkovic of Germany 6-3, 6-3. Petkovic ousted Errani at Roland Garros last year at the quarter-final stage before losing in the semis. There was disappointment though for another Italian, 2010 Roland Garros champion Francesca Schiavone, who lost 7-5, 6-4 to Andreea Mitu of Romania. Ranked 100th in the world, Mitu is playing in her first French Open and her three wins in Paris this week were her first at Grand Slam level.

Her next opponent, with a quarter-final slot at stake will be 93rd-ranked Alison Van Uytvanck of Belgium, who ended the hopes of France's Kristina Mladenovic 6-4, 6-1. Van Uytvanck was 1-5 in Grand Slam matches coming into Roland Garros, but like Mitu she has been able to benefit in her quarter of the draw from the first round defeat of sixth seed Eugenie Bouchard at the hands of Mladenovic.