Courtroom drama “The Trial of the Chicago 7” and jazz period film “Ma Rainey’s Black Bottom” were the big winners at the Screen Actors Guild (SAG) awards, one of the last major ceremonies before the Oscars.

“The Trial of the Chicago 7,” set during a Vietnam War protest in 1968, took the prize for best ensemble with a cast that includes Sacha Baron Cohen, Eddie Redmayne, Frank Langella and Mark Rylance.

Langella credited writer and director Aaron Sorkin for the win, saying his “voice is the soul of this movie.”

All four of the winning film actors were people of color, the first time this has happened in the SAG awards’ 27-history.

Chadwick Boseman, who died of cancer last year at age 43, picked up another award for his final role as an ambitious 1930s trumpet player in “Ma Rainey’s Black Bottom.” Sunday’s SAG win positioned him as front-runner for his first Oscar at the Academy Awards on April 25.

Accepting on Boseman’s behalf, his widow Simone Ledward Boseman cited a saying from the late actor himself. “If you see the world unbalanced, be a crusader that pushes heavily on the see-saw of the mind.”

Viola Davis won best actress for playing a jazz diva in “Ma Rainey,” besting presumed favorites Frances McDormand for “Nomadland” and Carey Mulligan in revenge drama “Promising Young Woman.”

The SAG awards, chosen by members of the acting union, are closely watched because actors form the largest voting group in the Academy of Motion Picture Arts and Sciences, which organizes the Oscars.

The win for “The Trial of the Chicago 7” boosted the film’s chances of winning the best picture Academy Award in a year that has seen modern recession-era movie “Nomadland” grab many of the pre-Oscar awards.