Rafael Nadal, Roger Federer enter the fray

PARIS (Reuters) - After a subdued Sunday start at the French Open, the big guns are unleashed on Monday when three-times champion Rafael Nadal and world number one Roger Federer start their campaigns on the Roland Garros clay.

Nadal, unbeaten at the French Open since making his debut in 2005, faces 20-year-old Brazilian qualifier Thomaz Bellucci on Centre Court, and should expect easy progress against a man with a solitary ATP Tour win to his name this season.

Federer, winner of just one minor title at Estoril in 2008, has been sidelined to Court Suzanne Lenglen for his opener against big-serving American Sam Querrey.

Spanish 12th seed Tommy Robredo opens Centre Court proceedings against 2004 finalist Guillermo Coria of Argentina, and third seed Jelena Jankovic will hope to join fellow Serb Ana Ivanovic in the second round when she faces Romanian lucky loser Monica Niculescu.

Eighth seed Venus Williams, beaten by sister Serena in the 2002 final, faces Israel's Tzipora Obziler while home hope Richard Gasquet, seeded eight, plays fellow Frenchman Florent Serra.

Former world number one Amelie Mauresmo, who has slipped down the rankings and is seeded a lowly 22nd, plays Ukraine's Olga Savchuk in the last match on Centre Court.

(Writing by Miles Evans, editing by Pritha Sarkar)