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."

Australian Open runner-up Dominika Cibulkova reached round two with a 7-5 6-0 victory over Virginie Razzano.

Cibulkova reached the semi-finals at Roland Garros in 2009, which had been the only time she had progressed that far in a grand slam until her stellar run in Melbourne.

Eighteenth seed Eugenie Bouchard made a fine start to her tournament, thrashing Shahar Peer 6-0 6-2, while seeds Sabine Lisicki and Flavia Pennetta also won.