The 30th SAG Awards will for the first time stream live from Los Angeles on Netflix to 260 million global subscribers, with Oppenheimer and Barbie the lead nominees.
Christopher Nolan's atomic epic is up for four awards, including SAG's top honour, best ensemble. But Greta Gerwig's Barbie is also up for four awards and could challenge Oppenheimer for best ensemble.
The SAG awards will come ahead of Oscar voting closing on Tuesday.
Three of the past four SAG ensemble winners have gone on to win best picture at the Oscars. Everything Everywhere All at Once, CODA, and Parasite all won at the SAG Awards before triumphing at the Academy Awards. The exception was the 2021 winner The Trial of the Chicago 7.
Among television nominees, Succession will look to add to its Emmy and Golden Globe hauls. It's up for five awards. Also in the mix are The Bear, Ted Lasso, Beef and The Last of Us.
The night's most closely-watched contests are in the lead actor awards.
Cillian Murphy (Oppenheimer) may have the slight edge for best male actor, though Paul Giamatti (The Holdovers) is neck-and-neck with him. The same could be said for best female actor, where either Lily Gladstone (Killers of the Flower Moon) or Emma Stone (Poor Things) could win.
In another feature of the night, the SAG Life Achievement Award will be given to Barbra Streisand. Among the presenters are a trio of A Devil Wears Prada stars: Meryl Streep, Anne Hathaway and Emily Blunt.
This year's SAG Awards follow a gruelling months-long strike in which the SAG-AFTRA union fought a bitter battle over a number of issues. Much of the work stoppage was prompted over changes in the film and TV industry brought on by streaming, a sea change led by Netflix.