Amanda Seyfried confessed to feeling "so liberated" during the filming of The Housemaid.
The 40-year-old star, who shared the screen with Sydney Sweeney in the mystery thriller, confessed she thoroughly enjoyed portraying a deranged housewife in the film.
Chatting to W Magazine, Seyfried revealed: "I star opposite Sydney Sweeney, and we have the same shoe size, are the same height, and we giggle the same way.
"It was so crazy - in some ways, that film is like Black Swan or Single White Female, but funny. I got to play so hard.
"The director, Paul Feig, would give me the strangest directions. He'd say, 'Okay, make [Sydney] think you're going to kiss her!' I felt so liberated."
Seyfried has had nothing but praise for Sydney, dubbing her co-star a "sweetheart" in a previous interview with Vanity Fair. She said: "I don't envy anything she's going through.
"I've spent a lot of time with her; we just hit it off immediately. She's a sweetheart.
"She's a very generous, kind person at her core. I have to be honest: I did not have a moment like she's having ever.
"[My Mean Girls costar] Lindsay Lohan, we're buddies, and it's really, really, really harmful to people to have that kind of overnight spotlight. Because any press, good or bad, is still a blinding spotlight, and you have to manoeuvre and negotiate your way around it and outside of it.
"It's acrobatics that I don't think most people are capable of figuring it out at that age."
Seyfried noted that a sudden leap to fame can be "dangerous". Yet, she commended Sydney for her handling of the increased spotlight.
She stated: "It's just dangerous, because when you have people s******* on you - or idolising you and following you around - it can't be good for your psyche. It can't make you feel safe in the world.
"But I actually admire the way Syd shows up for work. She always has a smile on her face, even if she's miserable.
"I hope it doesn't change. I hope she doesn't harden. I just want to keep watching her work."