Kim Kardashian and Kanye West Party With Rihanna, Jay-Z at 'Throne' After-Party in London

Jay-Z and Kanye West kicked off the European leg of their "Watch the Throne" tour in London on May 18 — that's cause for celebration, isn't it?

The rappers thought so! They threw an after-party at DSTRKT nightclub to toast their success at London's O2 Arena.

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Although Jay-Z's wife, Beyoncé, was not in attendance (we assume she's preoccupied with little Blue Ivy, and rightly so!), Kanye's love, Kim Kardashian, was there to help him celebrate. She looked sleek as always, in an LBD, dramatic black jacket, and gold T-strap shoes.

Rihanna also got in on the fun, and personified edgy chic with her black ensemble and red lips. If her Twitter is any indication, RiRi had an excellent time: "You know it was a good night when u wake up n run to your BFF's room like... How did I get in my bed? Did I walk? Stumble? Get carried?"

Oh, RiRi. We love you. We wonder if the friend is the one whose hair she's holding onto as they leave the party. Good lesson here, people! Don't get separated from your friends at the club, no matter what it takes!

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Also in attendance: Coldplay's Chris Martin and wife Gwyneth Paltrow, and Rob Kardashian and girlfriend, singer Rita Ora.