Edward Norton, left, and Michael Keaton accept the prize Sunday for outstanding performance by a cast in a motion picture for “Birdman” at the Screen Actors Guild Awards in Los Angeles.

Oscar hopes for “Birdman” got an enormous updraft over the weekend with big wins from the acting and producing guilds, possibly sending the comedy soaring over the perceived Academy Awards front-runner “Boyhood.”

Alejandro Gonzalez Inarritu’s elegantly crafted backstage romp won best ensemble Sunday night at the 21st annual Screen Actors Guild, a day after it also won the top honor at the Producer Guild Awards. Both guilds are seen as highly predictive of which film will triumph at the Oscars on Feb. 22.

Richard Linklater’s “Boyhood,” the acclaimed indie made with the unprecedented real-life time-elapse of 12 years, has long held as the awards seasons favorite. But “Birdman” fills the role of a classic Oscar winner, like “Shakespeare in Love,” as a celebration of showbiz. Its fortunes look especially bright considering the last seven Producers Guild Awards winners have also won best picture at the Academy Awards.

“Actors love this movie for showing the courage actors have to kind of go out there and lay it on the line,” “Birdman” star Michael Keaton said backstage at the SAG Awards. He accepted the best ensemble award with his co-stars including Emma Stone and Edward Norton.

Yet Keaton also lost at the SAGs, held Sunday at the Shrine Auditorium in Los Angeles. Instead, most outstanding actor went to “The Theory of Everything” star Eddie Redmayne, whose exceeding technical performance as Stephen Hawking has equally drawn raves. Looking down at his blue statuette — “this very wonderful skinny man,” he said — Redmayne dedicated the SAG Award to sufferers and victims of ALS.

The other Oscar favorites — Julianne Moore, Patricia Arquette and J.K. Simmons — all cemented their front-runner status.

Moore, widely considered the best-actress favorite, won most outstanding actress for “Still Alice,” in which she plays an academic with early onset Alzheimer’s disease. Accepting the award, she recalled an early lesson on the soap opera “As the World Turns,” in which she played twin sisters, good and evil.

“Then I realized it was super boring to act by myself,” said Moore.

Accepting the award for most outstanding supporting actor for his performance as a domineering jazz teacher in “Whiplash,” Simmons thanked all 49 actors in the drama.

“Boyhood” star Arquette added the latest in a nearly uninterrupted string of supporting actress awards. “This little movie is about human beings and it’s about bringing real life onto the screen,” she said.

Because actors make up the largest portion of the Academy of Motion Picture Arts and Sciences, the SAG Awards are considered one of the most telling Oscar previews. Individual acting winners usually mirror each other exactly, or very nearly. Last year, the top four winners — Matthew McConaughey, Cate Blanchett, Lupita Nyong’o, Jared Leto — all went on to win Academy Awards after first scooping up SAG awards.

The predictive powers of the SAGs have been more checkered in matching its top award with eventual best-picture Oscar winners. In the last six years, SAG best-ensemble and Academy Award best-picture winners have lined up three times (“Argo,” “The King’s Speech” and “Slumdog Millionaire”), while diverging just as often. Last year, the actors chose “American Hustle” over eventual Oscar winner “12 Years a Slave”; in 2011, they picked “The Help” over “The Artist”; and in 2009, “Inglourious Basterds” defeated “The Hurt Locker.”