Could this be the year for boldly going where no Oscar has gone before?

On a night of potential firsts, James Cameron's Avatar has a shot at breaking one of Hollywood's longest-standing taboos and becoming the first science-fiction film to win best picture.

The 3D blockbuster, which, with box-office receipts of $2.5bn (€1.8bn), is easily the most lucrative film ever made, is gaining late ground on The Hurt Locker, and is now 11/8 second favourite to walk away with tonight's biggest prize.

That would represent a victory for a genre which has for years been one of Hollywood's most reliable cash cows but has been prevented, perhaps for reasons of artistic snobbery, from winning a fair share of awards.

Only three sci-fi movies have even been nominated for best picture – E.T. The Extra Terrestrial, Star Wars and A Clockwork Orange – and all were pipped by unfancied rivals.

But attitudes could be changing: The Lord of the Rings chalked up victory for the "fantasy" genre in 2004, while this year's shortlist also includes the alien invasion satire District 9.

"It's a watershed year for science fiction," noted Cameron at last week's Visual Effects Society awards.

"We've got two up for best picture. That's never happened before. It would be a real milestone if it did win because Star Wars was nominated but lost to a small film. E.T., even though it was actually a small film, was nominated and didn't win either."

Avatar was being tipped for Oscar triumph from the beginning of 2010, after it scored a double victory at the Golden Globes in January.

Cameron won the director gong for the movie at the US ceremony in an echo of his success 12 years before, when Titanic received best drama and the directing prize before sweeping the board at the Academy Awards.

In his speech, Cameron praised ex-wife Kathryn Bigelow, who was also nominated as best director for her tense drama about an elite bomb disposal team.

"Frankly, I thought Kathryn was going to get this. She richly deserves it," Cameron said.

Avatar recently surpassed Cameron's Titanic - and saw the director beat his own record - when the film became the highest grossing movie in history.

The Hurt Locker has been gathering steam in recent weeks, cleaning up at the Baftas with six awards, while Avatar, said to be the most expensive film made, won two.

Bigelow also triumphed at the Directors Guild of America awards, becoming the first woman to win the guild's top honour.

She is only the fourth female best director nominee in Oscar history and would be the first female winner.

Tonight's show is hosted by Steve Martin and Alec Baldwin.