"Maybe it's presumptuous to say this, but from a director's point of view he's the Holy Grail of actors, isn't he? At least he always was to me. Like, 'that's the man, that's the man.'"

That's Paul Thomas Anderson talking about Daniel Day-Lewis. And while it is customary for directors to sing the praises of their stars, the awe in Anderson's voice is palpable as he recounts the five months he spent working with the actor last year in Marfa, Texas.

Their project together, "There Will Be Blood," is a roiling, early-20th-century epic about greed and God. It opened last week in New York and Los Angeles to qualify for Academy Awards consideration. Day-Lewis is surefire for a best-actor nomination.

"The honor and the privilege was not lost on me," Anderson, 37, said about working with Day-Lewis, who won an Oscar in 1990 for "My Left Foot" and has been nominated twice since, for "In the Name of the Father" and "Gangs of New York." "But it's funny because that sense fades away as you're making the movie.

"It wasn't until about halfway through editing when I kind of sobered up a little bit and thought, I can't believe it, he is absolutely incredible, isn't he?"

The tales of Day-Lewis' dedication, his total immersion in a character, are legend: He spent days in an Irish prison to prepare to play the wrongly convicted Gerry Conlon in "In the Name of the Father." During his time on the set of Michael Mann's "The Last of the Mohicans," Day-Lewis went barefoot, built a canoe, tracked and skinned animals, and took his flintlock with him to dinner.

For the role of Daniel Plainview, an early-20th-century prospector who becomes an oil baron — a character loosely based on petro-millionaire Edward Doheny — Day-Lewis would prowl the ranch where shooting took place, and where period oil derricks and an entire frontier town, Little Boston, had been constructed. He'd be scowling and glaring at costars: Plainview is not nice, and Day-Lewis began inhabiting that not-a-nice-guy-ness.

But the actor, who is 50 and lives in Ireland and New York with writer and filmmaker Rebecca Miller and their three sons, isn't keen to talk about his process, where his performance comes from.

Part of it, obviously, comes from the script — in this case, Anderson's freewheeling adaptation of the Upton Sinclair novel "Oil!"

"Paul Thomas Anderson is a remarkable writer," said Day-Lewis, reached on the phone in New York a little later the same day that Anderson was interviewed. Anderson's previous work includes "Boogie Nights," "Magnolia" and "Punch-Drunk Love."