LOS ANGELES - Hollywood was buzzing with anticipation as the race for Oscar glory prepared to enter its final phase with the announcement of nominations for the 79th Academy Awards.
The Academy of Motion Picture Arts and Sciences was preparing to go into lockdown at its Beverly Hills offices ahead of Tuesday's dawn announcement at 5:38 am local time (1338 GMT).
"No cell phones will be allowed into the building and we're cutting off Internet access," Academy spokeswoman Toni Thompson told AFP. "We do this every year to stop news getting out before the announcement."
The sense of excitement swirling around the nominations has been heightened by the fact that experts are predicting one of the most open races in years for the coveted best picture Oscar.
The nominations announcement, which will be made by Academy president Sid Ganis and actress Salma Hayek, serves as an effective starting pistol for four frenzied weeks of lobbying ahead of Tinseltown's big night on February 25.
Although no one movie is being tipped to dominate across multiple categories, clear front-runners have emerged for the top Oscars -- best picture, best director, best actor and actress.
The race for best picture has been thrown wide open by the surprising victory of offbeat comedy "Little Miss Sunshine" at Saturday's Producers Guild of America awards.
The low-budget independent film upset rivals such as Golden Globes winner "Babel," Martin Scorsese's gangster drama "The Departed" and the uplifting musical "Dreamgirls" to take the award.
It now seems certain to earn a nomination for best picture alongside those three films and royal drama "The Queen."
"'Sunshine' winning the Producers Guild Award has given it a sunburst of momentum," said Tom O'Neil, an Oscars pundit with the Los Angeles Times' theenvelope.com. "It has changed the complexion of the race completely."
In the best director category, Scorsese, the overwhelming favorite to win this year's award having been passed over on five previous occasions, is likely to be the first name on most voters' ballots.
"Babel" director Alejandro Gonzalez Inarritu is also a certainty, along with Bill Condon of "Dreamgirls" and Stephen Frears of "The Queen."
However the husband-and-wife team behind the popular "Little Miss Sunshine," Jonathan Dayton and Valerie Faris, may be squeezed out by Clint Eastwood, who has won admirers for the achievement of helming back-to-back war movies, "Letters from Iwo Jima" and "Flags of our Fathers."
The veteran actor-director is a perennial favorite with the Academy of Motion Picture Arts and Sciences' nearly 6,000 voters, with two best director awards already, 1992's "Unforgiven" and "Million Dollar Baby" two years ago.
If Dayton and Faris are nominated, however, it would suggest a definite tilt towards "Little Miss Sunshine".
"If they make it into the directors nominations it suddenly makes 'Sunshine' a serious contender for best picture," said O'Neil. "It would be hard for the film to win if they aren't nominated."
International bookmakers currently list "Dreamgirls" as the favorite for best picture, amid speculation that the Academy may want to reward an upbeat picture after last year's Oscars were dominated by weighty dramas such as "Brokeback Mountain", "Crash" and "Syriana."
"Last year's awards could work in favour of 'Dreamgirls' and 'Sunshine,'" said O'Neil. "Other films in the running this year like 'Babel' or 'The Departed' are pretty dreary."
In the best actress race, Oscar-watchers are unanimous about the likely line-up, with three British stars expected to figure -- Helen Mirren, Judi Dench and Kate Winslet.
Meryl Streep is expected to earn her 14th Oscars nod for "The Devil Wears Prada" with Spain's Penelope Cruz completing the quintet for "Volver."
The best actor race is less clear-cut, with only two men viewed as certainties to earn a nomination.
Forest Whitaker is a safe bet for "The Last King of Scotland," in which he plays Ugandan dictator Idi Amin. Veteran Irish actor Peter O'Toole is also a shoo-in to win his eighth Academy Awards nomination, for "Venus," 45 years after his first, for "Lawrence of Arabia."
Leonardo DiCaprio's performance in "The Departed" could earn him a nomination too, with Ryan Gosling ("Half Nelson") and Will Smith ("The Pursuit of Happyness") the other tipped nominees.