The British actress appeared at the glitzy awards at the Beverly Hilton on Sunday night (08Jan17), where she stunned in a white Michael Kors gown and sparkly Tiffany & Co. jewellery.

While Sienna looked very composed as she walked the red carpet, she admitted to feeling anxious before she was set to take the stage to present the award for Best Director in a Drama, which was one of the last honours of the night.

"I was a few sheets to the wind at that point," she said during an appearance on The Late Late Show with James Corden on Monday night (09Jan16). "I was nervous, hence having a few bevies (drinks) - a couple of vodkas, yes."

Sienna, 35, went onto explain that she felt quite overwhelmed prior to presenting the award alongside her Live By Night co-stars Ben Affleck and Zoe Saldana, as she was waiting in a room with some of Hollywood's most handsome stars.

"It's quite nerve-wracking. I was backstage and it was Brad Pitt, and Ben Affleck and Jon Hamm. That in itself was a pretty nerve -inducing experience," she laughed. "It was like, 'There is too much beauty in this room!'"

However, Sienna has also shared that she wasn't at all intimidated by Affleck when they filmed Live By Night, because he made her laugh all of the time, even during sex scenes.

"Ben and I are like brother and sister, thank God, so there was no awkwardness. There was just a lot of stupid giggling. He's very professional - I am not, but he is," she shared to E! News recently. "There will be some outtakes from that (scene) where I have to walk out of the room... because I just have tears running down my face."