For weeks, Britons Daniel Day-Lewis and Julie Christie have looked like sure bets to win the coveted best actor and actress Academy Awards, but in the days ahead of Sunday's gala ceremony, momentum has shifted.

Hollywood enjoys surprises on the movie industry's most prestigious night, and pundits think popular actor George Clooney and little-known French actress Marion Cotillard would be wise to start practicing their acceptance speeches.

There is no such thing as a shoo-in at the Oscars. Hollywood is a town of bull-headed, contrary-minded people, said Tom O'Neil, columnist for www.TheEnvelope.com.

Day-Lewis, 50, an actor known for lengthy preparation, is well-liked by Academy voters. He won an Oscar playing a man who overcomes cerebral palsy in 1989's My Left Foot, and has been nominated two other times for In the Name of the Father and Gangs of New York.

This awards season, he has earned numerous honors playing a sadistic, early 20th century oil prospector in dark drama There Will Be Blood -- only his fourth film in a decade. Yet, Oscar watchers say, his work is as sharp as ever.

Day-Lewis hasn't really lost anything. Even if you don't like the movie, it's a big performance and he dominates the film, said Pete Hammond, movie critic for Maxim magazine.

But opinions are split over the film's overall appeal, and Oscar voters prefer inspiring characters over villains.

Clooney's never been nominated for lead actor and in 'Michael Clayton' he's a hero who sheds his evil ways, so the question is, how Clooney-crazy is Hollywood? said O'Neil.

Moreover, Clooney's Michael Clayton, a thriller about unmasking corporate misdeeds, is well-liked with seven nods including best picture, director and supporting actress and actor.

Johnny Depp (Sweeney Todd The Demon Barber of Fleet Street), Tommy Lee Jones (Into the Valley of Elah) and Viggo Mortenson (Eastern Promises) are also best actor nominees.

MORE DRAMA THAN EXPECTED

Julie Christie, 66, who has managed to be both revered and reclusive, has won universal acclaim for her portrayal of a woman with Alzheimer's disease in Away From Her. The role earned her the Golden Globe award for best dramatic actress.

It's a good film that deals with a relevant social problem in a realistic way, and people are always saying there are no good roles for women of a certain age, said Emanuel Levy, author of All About Oscar.

The actress earned her fourth Academy Award nomination and looked set to take home her second Oscar statuette 42 years after her win for the Swinging Sixties London movie Darling.

That was before Cotillard took the British BAFTA award on Christie's home turf on February 10 for playing singer Edith Piaf in the French-language movie La Vie En Rose. She also won the Golden Globe for best actress in a musical or comedy.

It is difficult to win when your movie is in a foreign language and it is not widely seen. But when people do see it, they are just blown away by her performance, said Hammond.

Oscar voters also favor youth. In the last 15 years, only two women over 50 -- including last year's winner Helen Mirren -- have won in the acting category. Cotillard is 32.

Cotillard would be the second best-actress winner for a foreign language film. The first was Sophia Loren.

Newcomer Ellen Page who plays a sarcastic pregnant teen in the comedy Juno could prove a wild card, with Laura Linney (The Savages) and Cate Blanchett (Elizabeth: The Golden Age) rounding out the nominees.