Paris, Sep 29 (IANS): Defending champion Rafael Nadal and 23-time Grand Slam champion Serena Williams advanced to the second round of the ongoing Roland Garros with straight-sets wins in their respective opening round matches.

On Monday, Nadal defeated Belarusian Egor Gerasimov 6-4, 6-4, 6-2 to reach the second round where he will face Mackenzie McDonald.

"It is a different Roland Garros. Totally different than we are used to… But for me this year is as special as every one at Roland Garros," Nadal said on court as per the ATP Tour website.

"I am going to keep trying my best. I am happy to be in the second round (after) a good start and now is the moment to go back to the hotel, have a good practice tomorrow and try to be ready for the second round," he added.

In the women's singles, Williams began her quest for a 24th Grand Slam title, surviving a topsy-turvy opening set to ultimately ease past fellow American Kristie Ahn 7-6(2), 6-0.

"The biggest difference was just confidence," the American said after the match as per the WTA website. "I just need to play with more confidence, like I'm Serena."

"So that was it. I just started playing like that, and I love the clay and I started playing like it, opening the court and moving and sliding," she added.

Up next for Williams is US Open quarterfinalist Tsvetana Pironkova.

Meanwhile, newly-crowned US Open winner Dominic Thiem also claimed straightforward victory as he defeated Marin Cilic of Croatia 6-4, 6-4, 6-2. However, Russia's Daniil Medvedev was unable to clinch his first win at the Roland Garros after suffering a shocking 6-4, 7-6(3), 2-6, 6-1 defeat against Hungarian Marton Fucsovics. It was the fourth successive first-round-exit for Medvedev at the Roland Garros.