Slumdog Millionaire follows a young Indian's life in contemporary Mumbai
Danny Boyle has been named best director by the Directors Guild of America for Slumdog Millionaire - a key indicator of Oscar success.
Only six times in the 60-year history of the awards has the winner failed to take an Oscar for best director.
The movie, about a Mumbai slum-dweller who takes part in a game show, has now won prizes at four major awards.
Boyle beat Frost/Nixon director Ron Howard as well as The Curious Case of Benjamin Button's David Fincher.
He also overcame competition from Gus Van Sant for Milk and The Dark Knight's director Christopher Nolan.
Slumdog Millionaire's cast won the ensemble prize at last month's Screen Actors Guild awards, and took four Golden Globes as well as securing success at the Producers Guild of America ceremony.
Danny Boyle will now be favourite to win the Academy Award
It has 10 nominations for the Academy Awards, to be held on 22 February.
Accepting his honour at the Los Angeles ceremony, Boyle noted the movie's own rags-to-riches story.
It almost went straight onto DVD after Warner Brothers closed down the arthouse label on which it was to be released.
DIRECTORS GUILD WINNERS
TV drama series: Dan Attias for The Wire
TV movie: Jay Roach for Recount
TV comedy series: Paul Feig for The Office
Musical variety: Brent Gunts for the opening ceremony, Bejing Olympics
Reality TV: Tony Croll for America's Next Top Model
Documentary: Ari Folman for Waltz With Bashir
Honorary membership: Film critic Roger Ebert (above)
But Fox Searchlight stepped in with a distribution deal.
Boyle, 52, said: "I should start by curiously thanking Warner Bros for actually having the grace to do the right thing, when I think it would have been a lot easier to do the wrong thing, and pass the film on to Fox Searchlight, who are an extraordinary bunch of people."
The award was presented by directors Joel and Ethan Coen, who won the same prize a year ago for No Country For Old Men.
Boyle joked backstage: "To step into the shoes of people like the Coen brothers, it's phenomenal. I have stolen from them all my career, in a naked and appalling way."
Other winners included Ari Folman, who took the documentary award for Waltz With Bashir - which is up for best foreign language film at the Oscars.
In the television awards, Paul Feig won the comedy prize for an episode of the US version of The Office, while Dan Attias took the drama prize for an instalment of the final series of The Wire.
Veteran film critic Roger Ebert was honoured with honorary life membership of the guild.
The guild's president, Michael Apted, noted the Chicago Sun-Times writer could no longer talk because of complications from thyroid cancer.
"We're happy that it didn't stop you from writing about our work," he said.
Steven Spielberg, Clint Eastwood, Martin Scorsese and Oliver Stone paid tribute to Ebert, who said in a statement recorded via a synthetic computer voice: "The motion picture is the art form I love above all others. It is the symphony, and you are the conductors."