When Ana de Armas signed on to play Marilyn Monroe in an upcoming film, she didn't expect to have such difficulty perfecting her voice. 

The "Knives Out" star, 32, revealed it took her nine months of coaching to get down Monroe's signature breathy voice. 

De Armas told the U.K. publication The Sunday Times, "It only took me nine months of dialect coaching, and practicing, and some ADR sessions."

She added, "It was a big torture, so exhausting. My brain was fried."

BEN AFFLECK, ANA DE ARMAS SPLIT AFTER ALMOST 1 YEAR OF DATING: REPORT

The 2021 biopic is titled "Blonde" and per IMDB will be "a fictionalized chronicle of the inner life of Marilyn Monroe."

It also stars Bobby Cannavale and Adrien Brody and was directed by Andrew Dominik.

Actress Marilyn Monroe will be the subject of an upcoming movie titled 'Blonde.'  ((Photo by Alfred Eisenstaedt/Pix Inc./The LIFE Picture Collection via Getty Images))

"I had a lot of thoughts as a woman in the industry, and even in general, about how things from the 1930s, 1940s, 1950s are so relatable to nowadays," de Armas mused. "And how if you don't have a strong base, with your family and so on, it's really hard to make it through — really hard."

2021 looks like a busy year for de Armas as she is also starring as a Bond girl in "No Time to Die" which is due to hit theaters on October 8, 2021, after multiple delays because of the pandemic

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The Cuban-born actress recently split with actor/writer/director Ben Affleck. They were first linked to each other in March 2020 after meeting on the set of their movie "Deep Water."

Ben Affleck and Ana de Armas broke up after nearly a year of dating.  (Getty/AP, File)

People magazine reported that the breakup happened because the stars were at "different points in their lives."

"There is deep love and respect there," a source told the outlet. "Ben continues to want to work on himself. He has three jobs lined up and he’s a solid father at home. They are both happy with where they are in their lives."

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Another insider close to the former couple added that "she broke it off."

"Their relationship was complicated," the insider added. "Ana doesn't want to be Los Angeles based and Ben obviously has to since his kids live in Los Angeles."