Julia Roberts, Abigail Breslin and Chris Cooper were among the cast of August: Osage County all gushing about co-star Meryl Streep at the Toronto Film Festival.
The drama, which stars Meryl as the pill-popping mother of a bitter daughter played by Julia, also stars Benedict Cumberbatch, Ewan McGregor, Dermot Mulroney and Juliette Lewis and was produced by George Clooney.
Julia revealed on the red carpet as the film premiered at the Canadian film festival: "It's not a magic trick. You think she's so great that she's just going to show up and 'poof' this puff of smoke, but she really works so hard, she's committed."
Chris added: "When the camera's rolling, to watch this woman, even if she's doing the same scene, she brings something new to it every take and any chance I have to tell people this - she's astounding!"
Little Miss Sunshine star Abigail, 17, confessed: "Just the whole cast was intimidating and scary and amazing. I was definitely very starstruck but they were all very welcoming and nice to me so I was very lucky."
August: Osage County is based on a Tracy Letts play that opened on Broadway in 2007 and scooped a cluster of awards including the Pulitzer Prize.
Dermot revealed he had to audition twice for the movie, despite being a friend of director John Wells.
He exclaimed: "Well John and I used to be neighbours, we knew each other, you think maybe that'd get me a break!"