Both ladies competed in a chic-off at the New York showing, oozing glamour in strapless dip-hem frocks.
Despite not appearing in the film, Olivia turned more than a few heads in a ravishing red gown by Osman.
The actress played the doting fiancée as she supported beau Jason Sudeikis whilst flashing her dazzling engagement ring.
She added a simple clutch by Jimmy Choo and nude heels by Casadei, upping the va-va-voom with a striking red pout.
And while her bright smackers looked totally dreamy, Olivia was worried about the risks of rocking such a loud lip, tweeting: "Wearing red lipstick like I think I'm a grownup. 50 bucks says it's on my forehead by the end of the movie. #WereTheMillersPremiere #spaz."
Luckily she pulled it off without a hitch - phew!
And while Olivia sizzled in red, Emma unleashed her inner vixen in a sultry number by Michael Kors.
The pretty blonde, who plays Jason and Jennifer Aniston's daughter in the film, flashed her gym-honed pins in the sophisticated gown.
She went for pared-back chic with plain heels by Casadei, highlighting her porcelain complexion with a touch of peach blusher and rosy lippy.
Also in attendance was Jennifer Aniston, who looked blissfully happy in an aubergine frock by Burberry with hubby-to-be Justin Theroux on her arm.
Altogether now; awwww!
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