“She is next-level incredible in this.”

For over a decade, Jennifer Aniston has been one of America’s television and film sweethearts. From her role as Rachel Green on Friends to her comedic turns in Horrible Bosses and We’re the Millers, Aniston continues to spark interest from fans everywhere. But now the 45-year old actress has taken on a different role: one that could get her an Oscar nomination.

On Monday at the Toronto Film Festival, Aniston showed a new side of herself in the film Cake: one that includes scars, greasy hair, and no makeup.

In the film, Aniston plays Claire, a woman suffering from addiction, rage, and suicidal depression who attends a chronic-pain support group.

“I let myself pretty much fall apart physically and that was really important for me, emotionally and physically,” Aniston said.

Aniston also mentioned that she did “quite a lot of homework” for the role.

“I have two girlfriends who have suffered from chronic pain and one who is actually a dear friend and a stunt woman who experienced a very severe accident and became addicted to pain meds,” she said. “For me it was really important to be true to what the medicine that I was taking physically would be doing to my body and at what point. That was actually kind of my biggest challenge as we were shooting out of order — having a ledger of where I was in my pain management and my physicality.”

But the role of Claire actually took a physical toll on Aniston herself.

“I wore a brace which someone told me was a brilliant idea, because I tend to slouch and it helped me to just keep that [posture],” she explained. “It turns out if you walk like that for five weeks you do start to actually become in pain.

“The one thing I did have to do was have some treatments on the weekends because I would have pinched nerves and pinched this and pinched that, just from the physicality of it.”

In the end, Aniston loved getting the opportunity to play an unglamorous character.

“It was extremely liberating to do that. I loved it. Because you know as women, we do feel we have to live up to an expectation,” she said.

“The truth of the matter is that that’s just not the way it is. We don’t always have our high heels on; we don’t always have our makeup on. This character was someone who had just basically given up on just even waking up sometimes. That’s what it required. That’s how I approached it.”

Anna Kendrick, who plays a member of Aniston’s support group in the film, spoke highly of The Good Girl actress.

“To be honest, while we were making the movie I just wanted to shout from the rooftops how incredible she was on set, and what an extraordinary performance she was giving,” Kendrick said. “She just brought it every day.”

Cake is currently up at the film festival. If picked up and released, it could enter the Oscar race this year. And talk is already out there about Aniston receiving the “big O” herself.

“Aniston proved way beyond cosmetic changes that she is the real thing,” wrote Deadline’s Pete Hammond. “She’s heartbreakingly good.”

Cake is directed by Daniel Barnz and also features Sam Worthington (Avatar) and Adriana Barraza.