After a stunning red-carpet appearance in London's West End, Renée Zellweger appeared to uncharacteristically let her hair down at the after-party for new film Leatherheads.

A red-faced Renée had clearly been in the party mood, as she was seen looking the worse for wear after the bash at the Automat restaurant in Mayfair.

And, while tottering out of the venue this morning, it looked like Renée had been attacked by a heavily slicked pair of lips.

Scroll down for more...

Squiffy: Renee appears to have taken advantage of the refreshments at the post premiere party for new film Leatherheads in London's Mayfair last night

V.v bad behaviour: Giggly Renee can hardly keep a straight face as she emerged from restaurant Automat looking somewhat worse for wear

Renée is hardly known for cutting loose, preferring to remain demure while the party kicks off around her.

But last night she obviously threw caution to the wind at the after-party for her film Leatherheads.

Scroll down for more...

Glamorous: Renee as she appeared earlier at the London premiere of new film Leatherheads in which she stars with George Clooney

Party hard: Renee looked stunning in her Marchesa gown - and partied in it all night

She was spotted knocking back drinks while in deep conversation with a bunch of her industry friends.

Still wearing her gorgeous plum-coloured strapless Marchesa dress she wore to the premiere earlier, the Bridget Jones star was obviously in the mood to have some fun.

Marchesa designers Georgina Chapman - the wife of Renee's friend and movie mogul Harvey Weinstein - and Keren Craig are the designers of Coleen McLoughlin's £100,000 wedding gown.

The red-faced Bridget Jones star had lipstick all over her shoulder and a big smacker on her cheek (who kisses someone on the shoulder?!).

Earlier in the evening, Renée along with Leatherheads co-star and director George Clooney strutted their stuff along the red carpet amid screams from adoring fans.

Gorgeous George was on fine form last night - despite partying into the wee hours that morning at Bungalow 8 with Jemima Khan and Mariella Frostrup.

Can't believe it's Clooney: Hollywood star George attracts an astonished glance from an onlooker as he leaves the after-party

Red carpet stars: Friends George and Renee are reunited onscreen in the 1920s themed American football romantic-comedy