Jared Leto won the first Oscar on Sunday at the 86th Academy Awards show, as anticipation mounted over who would take home the coveted best picture prize on Hollywood's biggest night of the year. Harrowing historical drama "12 Years a Slave," 3D space thriller "Gravity" and 1970s crime caper "American Hustle" are hotly tipped to take the top prizes at the Oscars, the climax of Tinseltown's annual awards season. Leto won the best supporting actor Oscar for his portrayal of a transgender woman suffering from AIDS in "Dallas Buyers Club," the first prize of a show likely to maintain suspense until the end. The actor and rock musician used his acceptance speech to send a topical message to people in troubled Ukraine and anti-government protesters in Venezuela. "To all the dreamers out there .. in places like Ukraine and Venezuela, I want to say, we are here. And as you struggle to make your dreams happen, to live the impossible, we're thinking of you tonight." - 'Surreal moment'' - The ceremony got underway at the Dolby Theatre after storm clouds lifted, allowing stars to hit the pre-show red carpet. Briton Chiwetel Ejiofor, up for best actor for "12 Years a Slave," was among the A-listers who strutted their stuff, as did his co-star Lupita Nyong'o, up for best supporting actress and stunning in pale blue Prada. "It's quite a surreal moment," Ejiofor told CNN, adding that "it would be amazing" to win. But he stressed: "One of the proudest things... is that people have received the film in the spirit in which it was made." Nyong'o added: "My heart is telling me it's going to be a good night." On the acting front, Cate Blanchett is favorite for her turn in Woody Allen's "Blue Jasmine," while Matthew McConaughey is widely fancied to strike Oscars gold for his portrayal of homophobic HIV-positive AIDS activist Ron Woodroof in "Dallas Buyers Club." - 'Very intense season' - On the eve of Hollywood's biggest night, "12 Years a Slave" scored a last-minute boost by winning best feature and best director for Briton Steve McQueen on Saturday at the Independent Spirit Awards. But experts agree that, while some categories may be seemingly settled, all bets are off for the big prize of the night, the best picture Oscar, which will be handed out at the end of the show hosted by US talk show host Ellen DeGeneres. DeGeneres opened with a monologue making fun of the storms which hit California on the eve of the Oscars. "It's been a tough couple of days for us here. It has been raining," she said, addressing the global audience. "We're fine. Thank you for your prayers," she dead-panned. The 6,000 or so voting members of the Academy of Motion Picture Arts and Sciences cast their ballots over 12 days starting on Valentine's Day and ending on Tuesday. - Too close to call - The best picture race is so close that the winner could come down to only a few votes, under the Academy's preferential voting system. Under the rules, voters rank all nine nominated films. They are: "American Hustle," "Captain Phillips," "Dallas Buyers Club," "Gravity," "Her," "Nebraska," "Philomena," "12 Years a Slave" and Martin Scorsese's "The Wolf of Wall Street." Those with the least first-place votes are dropped, and their votes given to the next highest-ranked nominees. This continues until one movie has 50 percent plus one vote. Topping nominations are "American Hustle" and Mexican director Alfonso Cuaron's "Gravity," with 10 nods apiece, followed by "12 Years a Slave," a true story of a free black man sold into slavery, with nine. Cuaron is the frontrunner for the best director prize, and his star Sandra Bullock earned high praise for her work in the spectacular space drama, prompting some to suggest she could cause an upset in the best actress race. But Australia's Blanchett remains the firm favorite in that category, despite a strong field also containing Meryl Streep ("August: Osage County"), Judi Dench ("Philomena") and Amy Adams ("American Hustle"). The star-studded Oscars broadcast will feature performances by Irish rockers U2, playing their nominated song from "Mandela: Long Walk to Freedom," and a first Oscars turn by veteran Bette Midler.