Roberts vs. Streep in "August: Osage County'

NEW YORK – Julia Roberts has a line in "August: Osage County," the all-star adaptation of Tracy Letts' Pulitzer Prize winner, that sums up the cheery worldview on display in this dysfunctional family free-for-all.

"Thank God we can't tell the future," Roberts' character, the oldest and seemingly most together of the three Weston sisters, sighs. "We'd never get out of bed."

"That was really the one line of mine that just knocks you out," Roberts said. "Because it's so true, and it's so heartbreaking. But you really can't live in that thought. … You just can't."

And Roberts, who delivers one of the strongest performances of her career in "August: Osage County" — literally going toe-to-toe in a living-room rumble with Meryl Streep — is not about to wallow in such doom. Wearing glasses and a beaming smile, the actress has taken a day to do interviews for her film, which goes into wide release next Friday.

Roberts and Streep received best actress nominations for the Golden Globes and Screen Actors Guild awards — Streep for lead actress, Roberts for supporting. And SAG nominated the entire cast — including Abigail Breslin, Chris Cooper, Benedict Cumberbatch, Juliette Lewis, Margo Martindale, Ewan McGregor, Dermot Mulroney, Julianne Nicholson, Sam Shepard and Misty Upham — for outstanding performance.

Streep is Violet Weston in the John Wells-directed take on the 2007 play. She's the malignant matriarch presiding over an unhappy family reunion. She pops pills, puffs cigarettes and has an unkind word for everybody. Oh yes, she has cancer, too.

Roberts is Barbara, the daughter who's moved away and married but who finds herself in the grim throes of a breakup. (Her husband, played by McGregor, has found a younger woman.) Barbara and Violet stare daggers; it's all contempt, and painful memories, between them.

Roberts says she was undaunted by the prospect of working with Streep, with her legendary ability to inhabit a role.

"She's amazing," offers Roberts. "But it's not daunting to be in Meryl's presence, to work with her, because she's so inviting. She doesn't hold you away to witness. She invites you into her orbit."

Set in small-town Oklahoma — "in the middle of nowhere close to anywhere" as Roberts nicely puts it — "August: Osage County" is an actor's marathon, a gabfest of finely tuned phrases. The actress says she and her castmates were constantly running lines with one another, rehearsing, reconsidering their scenes.

"I would come home some nights with no voice from screaming all day," she recalls. "But the amount of work we had was a saving grace, because you couldn't really allow yourself to collapse into thinking how sad and mean it all really is."

"Sad" and "mean" are not words that define Roberts, who has ventured to dark places in a few of her films ("Sleeping With the Enemy," "Closer," the more tortured stages of "Eat Pray Love") but whose screen persona is generally sunny, saucy, plucky, resilient.

"Well, actually, it was harder than I had anticipated," she said, laughing. "Because I think that, for me, at the center of all things is a true sense of optimism and happiness. And that just can't be found in this circle of people. … So it was challenging to try to find who [Barbara] really is, as opposed to just saying, 'Well, I'll go in there and I'll just start yelling and I'll yell all this stuff, and seem really mad.' "

Letts, the playwright and actor (he's Sen. Lockhart, a key player in the just-ended season of Showtime's "Homeland"), marveled at how Roberts found layers of meaning, and emotion, in his words.

"I feel silly saying this, but I said to her at one point, something along the lines of 'You should do this more often,' " he observed. "And her response was very quick, and very genuine. She said, 'Things like this don't come around very often. Scripts like this aren't exactly crossing the desk every day.'

"And that's a shame. She should have more opportunities."

Maybe she will. Roberts, 46, just wrapped up work on the screen adaptation of Larry Kramer's award-winning AIDS drama "The Normal Heart."

"I have the coolest job, I really do," says Roberts, who is married to Daniel Moder, a cameraman she met while filming the 2000 release "The Mexican." They have three kids. "And at the end of the day, you go home to the light, and have all the more appreciation for that. That's one of the upsides to going through all the Weston mire — is to go home and realize, 'Oh wait, my life's not like that!' "