Chastian, 35, who earned an Academy Award nomination for her performance in "The Help", said she thought Olivia De Havilland's Oscar-winning role would "terrify" her, reported Daily star.
She will lead the cast of the stage revival as Catherine Sloper, a shy young woman yearning for her wealthy father's acceptance.
"(I thought), 'Maybe if you're afraid of it (the role), you should look more into it.' I had a connection to her (Sloper). She's painfully uncomfortable and I used to be that," she said.
However, Chastain has been battling nerves ever since signing up for the job and she is struggling to decide on how best to portray the character ahead of rehearsals next month.
"I haven't been this unsure in a long time. I feel really, really terrified."