PARIS (Reuters) - Roger Federer faces a stern test of his French Open credentials on Saturday when he meets an in-form Mario Ancic in the third round.

Croat Ancic, who has the distinction of being the last player to have beaten the Swiss maestro at Wimbledon, has won his first two matches with something to spare and will be seeking to reverse a quarter-final loss to Federer at Roland Garros in 2006.

Their contest is the last scheduled match on Court Philippe Chatrier.

Women's top seed Maria Sharapova faces 32nd seed Karin Knapp and an easy ride will be top of her wishlist in the second match on the principal court.

The Russian, eager to win the French to complete her set of grand slams, has been forced into three-set contests in her opening two matches this year and faces the 20-year-old Italian for the first time in her career.

Svetlana Kuznetsova, the fourth seed and potential semi-final opponent of Sharapova, faces another Russian, 25th seed Nadia Petrova.

Meanwhile, victories for Julien Benneteau, Gael Monfils and Florent Serra would mean six French men would be in the last 16 for the first time since the game turned professional in 1968.

(Writing by Miles Evans; editing by Pritha Sarkar)