Rihanna is sending Katy Perry off to marriage with a bang. The R&B singer threw the pop star a fabulous bachelorette party in Las Vegas Saturday night and RadarOnline.com has the pictures.

PHOTOS: Kary Perry & Rihanna Go Backstage With The Cast Of KA By Cirque Du Soleil

Now we know why Katy Perry and fiancé Russell Brand were headed to Vegas Friday when he got arrested for tangling with a photographer at LAX.  Rihanna was throwing the bride-to-be a Sin City bash!

Fortunately Katy still got there in time, and the girls plus 25 of their closest friends started Saturday night by seeing a performance of KÀ by Cirque du Soleil at MGM Grand.

PHOTOS: Katy Perry In A Hot Red Bikini

After the performance, they headed backstage for a meet-and-greet with the amazing cast.

Then it was on to dinner and a long night — and early morning — of clubbing.

PHOTOS: Katy Perry Has A Marilyn Monroe Moment

And nobody got arrested!

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