Rihanna Victoria's Secret Fashion Show: Justin Bieber, Bruno Mars Perform as Lingerie Models Rock Runway, RiRi Gets Sexy Backstage [VIDEO]

Pop stars Rihanna, Justin Bieber, and Bruno Mars performed at the 2012 Victoria's Secret Fashion Show Wednesday evening (Nov. 7) as sexy, lingerie-clad models rocked the fierce runway for the annual, pre-holiday celebration. Rihanna performed her newest single "Diamonds" and closed out the catwalk with her hit "Fresh out the Runway" - Mars performed "Locked Out of Heaven" and "Young Girls" while Bieber performed "Beauty and the Beat" and "As Long as You Love Me" to a crowd of screaming, applauding fans.

While the Victoria Secret's Angels strutted down the runway in extravagant, beautiful, and robust angel wings, the three pop stars crooned in the background to provide a fun, energetic vibe. Rihanna kept her own amongst the crew of gorgeous models during her finale performance - decked out in a sheer pink dress highlighted by a pink bra-and-undies set and killer pink boot heels. Check out clips of the performances here:

Before the show, Victoria's Secret and CBS announced that each company had donated contributions to Hurricane Sandy Relief efforts - CBS will also broadcast a Victoria's Secret Fashion Show one-hour special on Dec. 14.

The Victoria Secret's Fashion Show is an extravagant production - most of the models adorn costumes which typical Victoria Secret's shoppers would never actually purchase. The catway was divided into six sections: Circus (Featuring contortionists and a sword eater), Dangerous Liaisons, Pink is Us, Silver Screen Angels, Angels in Bloom, and Calendar Girls (here, Bruno Mars adorably serenaded a model for each month of the year).

It looks like RiRi also had some fun backstage... check out her Twitter page for more sexy behind-the-scenes photos.

According to Bieber (who danced with models around a giant prop pinball machine during his "As Long as You Love Me" performance) - "It's like a dream come true... I would rather be here than anywhere in the world."

For a great collection of Victoria's Secret Fashion Show 2012 photos, go here.