Mandy Moore "wasn't ready" for her character's fate on 'This Is Us'.

Mandy Moore has discussed her acting challenge

Mandy Moore has discussed her acting challenge

The 38-year-old actress stars as Rebecca Pearson in the hit drama series, and Mandy has discussed the challenge of playing a character who is battling Alzheimer's disease.

Mandy said: "I don't know if there is a way to brace anybody.

"I wasn't braced for it. I wasn't ready. I had no idea what I was about to read or what we were all going to endeavour to do. I didn't know how [series creator] Dan [Fogelman] was going to flesh out the end."

The actress believes there's something "surprising" about the storyline.

She told Entertainment Weekly: "I would encourage people to come in with an open mind, and I'm sure they know where this is heading, but I think it's surprising. I imagine that this is [a] very real way for some people to imagine the end of their life."

Meanwhile, Milo Ventimiglia previously described Mandy as the "best" on-screen partner he's ever had.

The 44-year-old actor - who plays Jack Pearson in 'This Is Us' - also hailed the actress' "commitment" and "dedication" to her work.

He explained: "I've got to say she has been probably in my 26 years in front of the camera, the best partner I've ever had - her commitment, her dedication, her growth as an artist.

"The audience, you guys get to watch the show in its entirety. I get to sit there in front of her, or stand in front of her, or lay in a bed next to her and watch front row what she does and how impactful it is, the work is to her. And I've only seen it grown. So, it's been a pleasure to be her TV husband for six years.

"At the same time, closing this chapter, I'm very excited to see what Mandy does next because she's such a force."