Oscars 2016: Chris Rock Cracks Tough Race Jokes

California: Oscars host Chris Rock opened the annual show of glitz and pageantry honoring cinema's finest Sunday with a salvo of hard-hitting jokes targeting the lack of racial diversity among the nominees.

Tinseltown's elite gathered for the glittering celebration with survival epic The Revenant leading the charge for golden statuettes - but a row over the lack of ethnic minority acting hopefuls overshadowed the proceedings.

"Well, I'm here at the Academy Awards -- otherwise known as the white People's Choice awards. You realize if they nominated hosts, I wouldn't even get this job. Y'all would be watching Neil Patrick Harris right now," joked Chris, 51, as he began his opening monologue.

For the second year running, all 20 nominees in the main acting categories are white, and an angry social media backlash under the hashtag #OscarsSoWhite has grabbed the awards season headlines.

An audience expected to number several hundred million around the world tuned in as Chris, who is hosting despite calls for him to join a boycott, gave the Academy members a tongue-lashing from the start.

Insiders say he completely rewrote his opening monologue in the wake of the scandal to hold the Academy's 6,000-plus voting members, overwhelmingly white men, to account.

"Things are going to be a little different at the Oscars. This year, in the 'In Memoriam' package, it's just going to be black people that were shot on their way to the movies," Rock joked.

Team Leo

Formalities for the 88th Oscars got underway with celebrities arriving on the red carpet under hazy blue skies at Hollywood's Dolby Theatre.

Best supporting actress nominee Alicia Vikander floated in a strapless pale yellow Louis Vuitton gown that had Oscar watchers on Twitter comparing her princess look to that of Belle in the Disney classic Beauty and the Beast.

First prize went to filmmaker Tom McCarthy, who bagged an Oscar for best original screenplay for Spotlight, a searing look at the Boston Globe's investigation into child sex abuse in the Catholic church.

And Adam McKay and Charles Randolph took the adapted screenplay Oscar for The Big Short - another best picture contender.

Analysts have predicted that Sunday will be a night of long overdue glory for old Hollywood hands who have previously missed out.

Jaws will drop if best actor doesn't go to Leonardo DiCaprio for The Revenant, 22 years after his first of five acting nominations.

"Don't know about u but I'm rooting for LEO! He's blessed us w/ years of his storytelling, he deserves this!" tweeted pop diva Lady Gaga.

A widely-anticipated best supporting actor Oscar for Sylvester Stallone, who reprises his turn as underdog boxer Rocky Balboa in Creed, would be one of the stories of the night, almost four decades after his only other nominations -- for best actor and screenplay for the franchise's original outing, Rocky.

The 69-year-old shared a picture on Instagram of him dressed in a dark blue dinner jacket with black and blue lapels and a black shirt and bowtie, captioned: "On my way to the Oscars... It's been a memorable year."

First-time nominee Brie Larson looks to be a lock for best actress, having dominated the awards season with her performance as a kidnapped mother in Room.

Best Supporting Actress favorite Alicia Vikander won for her role in The Danish Girl. She was competing with Carol star Rooney Mara, on her second nomination, and previous best actress winner Kate Winslet, acclaimed for her work in Steve Jobs.

Alejandro Gonzalez Inarritu's The Revenant is the overall frontrunner, with 12 nominations, followed by George Miller's stark action epic Mad Max: Fury Road with 10 and Ridley Scott's space adventure The Martian, with seven.

Surprises will happen

The Gold Derby website, which aggregates experts' predictions, has The Revenant in the lead for best film, but analysts are split on whether Mr Inarritu will also pick up best director for the second year running following his win for Birdman.

"I think The Revenant will win best picture and the director will go to Miller," said Hollywood analyst Anne Thompson.

"It would be unlikely that the Academy would reward a genre sequel like 'Fury Road' with best picture, but they have gone with directors like Ang Lee and Alfonso Cuaron for well-mounted spectacles like Life of Pi and Gravity."

"As many people are saying, this is an unusual year when surprises will happen," she added.

The night will also feature some social activism: several stars including Oscar winner Patricia Arquette and past nominee Steve Carell will wear bracelets to promote a campaign against gun violence.

And Vice President Joe Biden will introduce a song by Oscar nominee Lady Gaga to push an initiative tackling sexual assault on US university campuses.

Gaga sang a duet with Elton John on Saturday at his pre-Oscars pop-up concert in West Hollywood, which drew thousands of fans to the Sunset Strip.

John organized the free event to thank the city for hosting his annual Academy Awards viewing party to raise funds for his AIDS foundation.