'Parasite', '1917' lead Oscars field after early awards

The international film category was formerly named best foreign-language film but was changed this year to reflect a more inclusive attitude.

"I applaud the direction that this change symbolizes," Bong said in Korean, speaking through an interpreter.

"Parasite," which focuses on the wealth gap in South Korea, is also seen as a front-runner for the coveted best picture prize, which could make for a historic night - no non-English language film has ever won the top prize at the Academy Awards.

The best picture Oscar, to be announced at the end of the three-hour show, is thought to be a three-way race between "Parasite," British director Sam Mendes' immersive World War One movie "1917" from Universal Pictures , and "Once Upon a Time in Hollywood," Quentin Tarantino's love letter to show business, from Sony Pictures.

"1917" won three early awards on Sunday, for its stunning "one-shot" feel cinematography, for visual effects and for sound editing, while "Once Upon a Time" brought the first acting Oscar for Brad Pitt, who played a supporting role as a laid-back stunt man.

"I'm a bit gobsmacked to tell you the truth," said Pitt, who recalled his early days starting out as an unknown actor.

"'Once Upon a Time in Hollywood' - ain't that the truth?," he said, dedicating the Academy Award to his six children with former wife Angelina Jolie.

Laura Dern took home the Oscar for best-supporting actress for her role as a ruthless divorce lawyer in "Marriage Story."

"This is the best birthday present ever," said Dern, who will turn 53 on Monday.

Despite again having no formal host, the ceremony started with a surprise appearance by former hosts Steve Martin and Chris Rock, who delivered a string of barbed jokes about the lack of female directors and people of colour among this year's nominees.

"I thought there was something missing this year," said Martin.

"Vaginas?" quipped Rock, to loud applause.

Rock pointed out Cynthia Erivo, who played slavery-era freedom fighter Harriet Tubman in "Harriet" and who was the only actor of colour nominated this year.

"Cynthia did such a great job hiding black people that the academy got her to hide all the black nominees," said Rock.

In another surprise, rapper Eminem took the Oscars stage to perform "Lose Yourself," his 2003 Oscar-winning song from the movie "8 Mile."

"American Factory," about the decline of jobs in the industrial Midwest from former US President Barack and first lady Michelle Obama's new production company, won for best documentary.