Maria Sharapova once again showed the remarkable turnaround in her clay-court game as she cruised into the second round of the French Open.

The 2012 champion shrugged off an hour-long rain delay to defeat fellow Russian Ksenia Pervak 6-1 6-2 in 61 minutes.

Sharapova, who in 2007 described herself as a “cow on ice” when playing on clay, would never have imagined that seven years later it would become her most successful surface.

Five of her last six titles have come on clay, including her only grand slam since 2008, while until losing to Ana Ivanovic in Rome earlier this month, she had gone unbeaten on the surface against every player apart from Serena Williams for three years.

Williams remains the major obstacle, though, and they are likely to meet in the quarter-finals next week in a rematch of last year's final.

Sharapova said: "The clay was very difficult for me, because I had never had mental confidence that I was able to play a three-hour match and have the opportunity to play in the semi-finals or finals.

"I wouldn't say I was physically weak, but I didn't recover that well and I wasn't strong enough.

"It took me years to build that confidence in my body and my legs getting stronger and recovering on the court to make it a surface that I actually loved playing on, even if the conditions are like this.

"I think it was one of the biggest individual goals I had, because I realised that I needed to do something about it and I think I just took it upon myself.

"It's almost like getting away from that fear, 'Okay, you can slide and you can get back in the court'. You don't need to just hang around by the post on the side, it's okay to get back on the court and play your game again."

Sharapova is seeded only seventh this year, partly because of shoulder problems at the end of 2013 that brought an early end to her season.

The Russian had to completely remodel her serve after shoulder surgery in 2008 and she revealed new coach Sven Groeneveld has helped her tweak it again.

She said: "Once Sven got on board we worked on a few things just to modify - nothing drastic, but a little thing here and there."

Former US Open champion Sam Stosur dropped just two games against Monica Puig, despite five stitches in her leg from an accident in the gym on Wednesday night.

The 19th seed said: "I didn't know what I had done. I thought it was really bad. So I saw everything flashing before my eyes. I can't feel anything when I'm playing, thankfully. The stitches are fine. It's healing well."

Eighteenth seed Eugenie Bouchard made a fine start to her tournament, thrashing Shahar Peer 6-0 6-2.

The Canadian only arrived in Paris on Saturday night after winning the first WTA Tour title of her career in Nuremburg.

She said: "It was tough, for sure. I flew right after the final and had one day of practice. But that's always a good problem to have. I feel like I'm playing well on the court, so I'm just trying to keep the flow going."

Australian Open runner-up Dominika Cibulkova and fifth seed Petra Kvitova were both straight-sets winners, while there were also victories for Sabine Lisicki, Flavia Pennetta, Alize Cornet, Andrea Petkovic and 18-year-old Taylor Townsend on her grand slam debut.

On Tuesday, fourth seed Simona Halep opens proceedings on Court Philippe Chatrier against Alisa Kleybanova, while 11th seed Ana Ivanovic meets rising French star Caroline Garcia.

Australian Open champion and second seed Li Na is on Suzanne Lenglen against Kristina Mladenovic and Caroline Wozniacki plays Yanina Wickmayer.