Ben Affleck's Iran hostage drama "Argo" goes into Oscars weekend a whisker ahead of Steven Spielberg's presidential "Lincoln," but the race is one of the most unpredictable in recent memory.

Veteran director Spielberg, bidding for his first best picture Oscar since "Schindler's List" in 1994, tops the nominations with 12 nods -- but "Argo" has cleaned up in Hollywood's awards season so far, despite having only seven.

Although he started the season two months ago in front, Spielberg may have to settle Sunday for the best director award -- one that Affleck cannot beat him to, having not been nominated in the category, in a perceived snub.

But again here there could be an upset, with rivals including Taiwan-born Ang Lee for "Life of Pi," David O. Russell for "Silver Linings Playbook," or even Austrian dark horse director Michael Haneke for Cannes-topping "Amour."

One near-certainty Sunday is that "Lincoln" star Daniel Day-Lewis will be named best actor, a record third for the British-Irish actor after wins in 1990 for "My Left Foot" and in 2008 for "There Will Be Blood."

The diffident Day-Lewis, known for his meticulous preparation -- he spent weeks in a wheelchair before playing Christy Brown in "My Left Foot" -- has been modest despite repeatedly taking the stage for acceptance speeches.

"Members of the Academy love surprises, so about the worst thing that can happen to you is if you've built up an expectation," he said, after winning the Screen Actors Guild (SAG) best actor award last month.

"I think they'd probably be delighted if it was anybody else," he added.

For best actress, the early favorite was Jessica Chastain, playing a CIA agent hunting Osama bin Laden in "Zero Dark Thirty," but the clever money is now on Jennifer Lawrence for her turn in "Silver Linings Playbook."

Lawrence, star of the "Hunger Games" blockbuster franchise, has won praise for moving out of her comfort zone as mixed-up widow Tiffany to Bradley Cooper's recovering bipolar Pat, in the romantic comedy with an edge.

The best supporting actress race is more open, although Anne Hathaway is probably still the frontrunner for her heart-wrenching turn in musical adaptation "Les Miserables," which is also nominated for best picture.

The most unpredictable race of all is perhaps for supporting actor, with Hollywood legend Robert De Niro tipped by some for playing Cooper's father in "Silver Linings Playbook."

But strong rivals in the category include Austrian Christoph Waltz as a white bounty hunter who frees Jamie Foxx's black slave in Quentin Tarantino's blood-spattered "Django Unchained," as well as Tommy Lee Jones in "Lincoln."

On the foreign front, the clear frontrunner is "Amour," which won the Palme d'Or at last year's Cannes Film Festival for its heart-wrenching portrayal of an elderly couple coping with encroaching physical and mental illness.

Its French female lead, Emmanuelle Riva, could even cause an upset in the best actress category, some critics believe. If she did, she would be only the sixth performer to win an Oscar in a language other than English.

Riva, who will be 86 on Sunday, is coincidentally also the oldest ever best actress nominee, and up against a shortlist including the youngest ever nominee, nine-year-old Quvenzhane Wallis for "Beasts of the Southern Wild."

"Amour" ("Love") is also among the nine films nominated for best picture, although it is not seen as a favorite there.

On a more colorful note, the best animated feature contest is widely seen as a battle between Scottish-themed princess adventure "Brave" and "Wreck-It Ralph," about a video game villain fed up with being the bad guy.

The fast and fun movie pays subtle homage to generations of computer games, in a feel-good story appealing to both mainstream cinema-goers and hard-core animation filmmakers at the Academy of Motion Picture Arts and Sciences.