Oscars diversity flap puts host Chris Rock in hard place

(Updates with red carpet opening, protest nearby, quotes)

* Chris Rock to break silence on diversity in opening monologue

* 'Revenant,' 'Big Short,' 'Spotlight' vie for best picture

* DiCaprio, Stallone, Brie Larson favorites for acting honors

By Jill Serjeant

LOS ANGELES, Feb 28 (Reuters) - Suspense and surprises mark the Academy Awards ceremony on Sunday after a rollercoaster awards season dominated by the #OscarsSoWhite controversy and no clear front-runner for the top honor of best picture.

It (Other OTC: ITGL - news) 's the movie industry's biggest celebration, but all eyes this year will be on Oscars host Chris Rock, the outspoken black comedian who is expected to take aim at a Hollywood diversity crisis that produced an all-white acting nominee line-up for the second year running.

"I think Chris Rock will address it head on, which is exactly what the show and the Academy needs," said Variety awards editor Tim Gray.

Director Spike Lee and actor Will Smith have shunned the Academy Award ceremony, although a wider Oscar boycott largely failed to gather steam with Hollywood A-listers.

Nevertheless, the under-representation of people of color in the film and TV industry has muted the congratulatory tone of awards season and prompted pledges to bring more women and minorities into the industry and the Academy.

In a break with tradition, Rock has given no interviews or hints of what he plans to say on Sunday's show, but in a cryptic tweet on Friday he wrote "see you Sunday...#blackout #Oscars".

As nominees and celebrities began the stroll down the red carpet outside the Dolby Theatre in the heart of Hollywood, protesters organized by civil rights leader Al Sharpton gathered nearby to make the case for more diversity at the Oscars.

"No matter how much glitter and how much of pomp they display this afternoon, it's a disgrace to have an exclusionary policy represent American culture," Sharpton told congregants at the Second Baptist Church of Los Angeles earlier in the day.

Sharpton has also called for Americans to "tune-out" the live telecast, the most watched non-sports TV event of the year.

Eva Williams-Bly, a 60-year-old who attended another black church where Sharpton spoke, said she was disappointed the Oscars are not as diverse as they should be.

But, she noted, "I've got too many other things to worry about," naming homelessness, affordable housing, racial profiling by police and voting participation.

BEST PICTURE TOSS-UP

Going into Sunday's ceremony, there was no consensus on which of the eight best picture nominees will take home the top prize.

"All the tea leaves are pointing in a different direction. It could be 'The Revenant', 'Spotlight,' 'The Big Short' or even 'Mad Max: Fury Road'," said Tom O'Neil, founder of awards website Goldderby.com.

With (Other OTC: WWTH - news) a leading 12 nominations, a Golden Globe and a BAFTA, 20th Century Fox's "The Revenant" with its ambitious tale shot in sub-zero temperatures has the epic qualities that traditionally appeal to the 6,200 voters of the Academy of Motion Picture Arts and Sciences.

If "The Revenant," directed by Mexican Alejandro Inarritu, wins best picture, it would mark the first time in Academy Awards history that a filmmaker directed two best picture winners in a row. Inarritu's "Birdman" won the 2015 best picture Oscar.

Open Road Films' "Spotlight", which traces the journalism probe of sex abuse in the Boston Catholic Church, is also in the mix, along with Paramount's Wall Street misdeeds comedy "The Big Short," pundits say.

Warner Bros well-reviewed "Mad Max: Fury Road" has 10 nominations and could turn out to be a rare action-adventure best picture winner.

Among the sure bets, popular Leonardo DiCaprio is seen as certain to win his first ever Oscar for his role as an 1820s fur trapper bent on revenge in "The Revenant."

Rising star Brie Larson, 26, is the heavy favorite to take home the best actress Oscar for her compelling depiction of an abducted young woman in indie movie "Room."

And 40 years after the first "Rocky" movie, Sylvester Stallone, 69, appears to have the sentimental edge over "Bridge of Spies" actor Mark Rylance in the supporting actor race thanks to Stallone's role as a boxing trainer in "Creed."

Oscar producers are hoping for fewer "thank yous" from the winners this year. In a bid to speed up the 3-1/2 hour ceremony and encourage more interesting acceptance speeches, a scrolling list will run on screens of the agents, managers, director and friends that each winner wishes to acknowledge.

(Additional reporting by Daina Beth Solomon; Editing by Mary Milliken and Cynthia Osterman)