Proving that she hasn't lost the guts and fun personality previously displayed on The Simple Life with Paris Hilton, Nicole took to the stage on Tuesday (18 February) like a trooper to get freaky with Britney.
And unsurprisingly, she appeared to have an amazing time!
Not only did the ex-reality TV star join in with the sexy 'Freakshow' performance like a pro, she even decided to go one step further by crawling on all fours in front of the packed crowd!
Surrounded by Britney's dancers, Nicole was pictured crawling along the stage in an all-black outfit and with her hair slicked back into a chic bun.
She later got up and hugged the chart-topping pop star, before being given a T-shirt with Britney's face on it.
As you can imagine, the 32-year-old songstress was extremely impressed with Nicole's contribution to her Vegas show, as she tweeted yesterday: "Can we all give a round of applause to @NicoleRichie for playing along in the show tonight? U looked hot crawling on all fours ;)."
If only we'd been there!
It's been a busy start to 2014 for Britney, as she is continuing her Las Vegas residency at the Planet Hollywood Resort and Casino.
She kicked off her residency shows last December and has been performing for most of February, treating fans to plenty of her popular tracks - old and new - including 'Toxic', 'Oops!... I Did It Again', 'Stronger' and 'Boys'.
On top of that, Britney has been experimenting with her image again and transformed into a brunette earlier this month, dying her trademark blonde hair just in time for Valentine's Day.
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