LOS ANGELES (AP) – Villainous roles snatched the supporting-acting prizes last night at the Academy Awards: 'Precious' co-star Mo'Nique as a contemptible mother and 'Inglourious Basterds' co-star Christoph Waltz as a sociable Nazi fiend.

Both performers capped remarkable years, Mo'Nique startling fans with dramatic depths previously unsuspected in the actress known for lowbrow comedy and the Austrian-born Waltz leaping to fame with his first big Hollywood role.

"I would like to thank the academy for showing that it can be about the performance and not the politics," said Mo'Nique, who plays the heartless, abusive welfare mother of an illiterate teen (Gabourey Sidibe, a best-actress nominee in her screen debut) in the Harlem drama 'Precious: Based on the Novel `Push' by Sapphire'.

Mo'Nique added her gratitude to the first black actress to win an Oscar, Hattie McDaniel, the 1939 supporting-actress winner for 'Gone With the Wind'.

"I want to thank Miss Hattie McDaniel for enduring all that she had to so that I would not have to," she said, adding thanks to Oprah Winfrey and Tyler Perry, who signed on as executive producers to spread the word on 'Precious' after it premiered at last year's Sundance Film Festival.

'Precious' also won the adapted-screenplay Oscar for Geoffrey Fletcher.

"This is for everybody who works on a dream every day. Precious boys and girls everywhere," Fletcher said.

Waltz's award was presented by last season's supporting-actress winner, Spain's Penelope Cruz, who gave Waltz a kiss as he took the stage.

"Oscar and Penelope. That's an uber-bingo," Waltz said.

Though a veteran stage and TV actor in Europe, Waltz had been a virtual unknown in Hollywood before Quentin Tarantino cast him as the prattling, ruthless Jew-hunter Hans Landa in his World War II saga.

"Quentin with his unorthodox methods of navigation, this fearless explorer, took this ship across and brought it in with flying colours, and that's why I'm here," Waltz said. "This is your welcoming embrace, and there's no way I can ever thank you enough."

The Iraq War drama 'The Hurt Locker' won its first category of the night, original screenplay for Mark Boal, who spun a story about the perils and pressures of a US bomb unit in Iraq. Jason Reitman and Sheldon Turner won the adapted-screenplay award for George Clooney's recession-era tale 'Up in the Air', which Reitman also directed.

The science-fiction blockbuster 'Avatar' also won its first category, for art direction.

With nine nominations each, 'The Hurt Locker' and 'Avatar' are tied for the Oscar lead. The competition between the front-runners does not heat up until later in the night, the two films nominated in categories that mostly come in the second half of the Oscar show.

The evening's last two categories, best director and picture, mark the two films' main rivalry, which is spiced up by a personal connection between 'Hurt Locker' director Kathryn Bigelow and 'Avatar' director James Cameron. They were married from 1989-91.

Cameron took the directing prize at the Golden Globes, but Bigelow earned the top honour from the Directors Guild of America, whose recipient almost always wins the same award at the Oscars.

If it happens, Bigelow would be the first woman in the 82-year history of the Oscars to win best director. Screenwriter Boal thanked Bigelow, calling her an "extraordinary and visionary filmmaker", and dedicated his Oscar win to the troops still in Iraq and Afghanistan, along with those who did not make it home. Boal also affectionately recalled his father, who died a month ago.

'Up' earned the third-straight Oscar award for Disney's Pixar Animation, which now has won five of the nine awards since the Academy of Motion Picture Arts and Sciences added a category for animated features.

The film features Ed Asner providing the voice of a crabby widower who flies off on a grand adventure by lashing thousands of helium balloons to his house.

"Never did I dream that making a flip-book out of my third-grade math book would lead to this," said 'Up' director Pete Docter. Pixar has a likely contender in the wings for next Oscar season with this summer's 'Toy Story 3', reuniting voice stars Tom Hanks and Tim Allen.

The country-music tale 'Crazy Heart"' won for original song with its theme tune 'The Weary Kind'.

The song category typically comes late in the show, after live performances of the nominees that have been spaced throughout the ceremony. Oscar producers tossed out those live performances this time in favor of montages featuring the songs and footage from the films they accompany.

'The Hurt Locker'and 'Avatar' lead an expanded field of ten best-picture nominees.

Oscar hosts Steve Martin and Alec Baldwin opened the show with playful ribbing of nominees, including Meryl Streep, Sandra Bullock, Woody Harrelson, Mo'Nique, Cameron and Bigelow. They also made note of Oscar organisers' decision to double the best-picture category from five films to ten.

"When that was announced, all of us in Hollywood thought the same thing. What's five times two?" Martin said.

Leaders of the Academy widened the best-picture category from the usual five films to expand the range of contenders for a ceremony whose predictability had turned it into a humdrum affair for TV audiences.

Oscar ratings fell to an all-time low two years ago and rebounded just a bit last year.