"I may have more options on clay," said the world number one Spaniard who stands 34-1 at the venue with his only loss coming in the third round in his first appearance in 2003.
Since then he's reeled off 32 straight match wins and is the only player in the post-1968 Open era to win six straight titles in a tournament.
"But I don't feel unbeatable, I know I can lose," said the player who should be coming into his element as his favourite part of the ATP season begins with a second-round match after a bye against either Julien Benneteau of France or Finn Jarkko Nieminen.
Nadal has scheduled a Tuesday practise session with Andy Murray, with the Scot sure to be watching the clay king closely as Murray tries to lift from a slump which has resulted in four straight losses in 2011.
Nadal said that previous years of success -- he won all four clay events he played in 2010 -- cannot be a guide for future performance but did admit that his 2010 title victory which broke an 11-month trophy draught was particularly pleasing.
"I played perhaps my best tennis ever here," as he won his sixth title on the site and did not drop a set along the way.
"It was the turning point of my season, I then played at my best clay level (in winning Rome and Madrid)."
Nadal said that each season starts afresh and is making no predictions about how well he might perform after a somewhat disappointing March in which he lost Masters 1000 finals in the US to Novak Djokovic, who is sitting out Monte Carlo with a knee injury.