Julia Gets a Surprise Kiss from Ewan McGregor

Julia Roberts made a rare appearance at the Toronto International Film Festival premiere Monday to support her film August: Osage County -- the big-screen adaptation of the Pulitzer Prize winning play by Tracy Letts -- which focuses on the dysfunctional Weston family, whose members are brought back together by a family tragedy to the Oklahoma house they were raised in.

And though she's one of the biggest movie stars in the world, Roberts was "overwhelmed" by the star-studded festivities -- including a surprise kiss from her handsome co-star Ewan McGregor.

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When the two found themselves unexpectedly side by side on the red carpet, McGregor gave her a kiss on the cheek, which got Roberts to flash her signature megawatt smile.

"That's my beauty secret for the red carpet," she joked. "Stand close to a Scotsman, how's that?"

But on a serious note, Roberts' secret to aging gracefully is staying down-to-earth.

"It's about the inside -- just happiness, and, you know, remembering who you are at all times," she told ET.

As for getting to work with the one-and-only Meryl Streep, who plays Violet, the drugged-up matriarch of the Weston family, she confirmed that it's every bit as amazing as one would expect.

"It was a dream," she says of the experience of filming with the living legend. "She's everything you want her to be in person -- she is."

Video: Watch Meryl & Julia's 'August' Mourning

Check out the video to hear how McGregor felt about adapting such a critically acclaimed play, Dermot Mulroney's experience filming with Streep and Abigail Breslin's surprising -- and slightly unhygienic -- red carpet beauty tip!
August: Osage County hits theaters on Christmas.