Rihanna Joins Jay-Z Onstage At Los Angeles Concert

Singer collaborates with Jay-Z for 'Run This Town,' then performs new single 'Hard.'

Justin Timberlake, Jessica Biel and Jamie Foxx all showed up for Jay-Z's concert Sunday night in Los Angeles, but what really got the fans hyped was Rihanna's appearance onstage.

The singer, who is gearing up to release her album Rated R on November 23, took the stage at UCLA's Pauley Pavilion to sing her part in "Run This Town." Wearing black-and-silver leggings, sunglasses, ankle boots, fingerless black gloves and an asymmetrical jacket, Rihanna danced around the stage and flashed a big smile as Jay rapped, according to video posted on her fan site, RihannaDaily.com.

Hov seemed excited to share the stage with the singer, who just days before, in an interview with Diane Sawyer, opened up about the night that Chris Brown assaulted her. At the end of the song, Rihanna gave Jay a big hug, smiled, and blew kisses and waved to her fans. "Los Angeles, make some noise!" she called out.

"RiRi, you ready?" Jay asked, and Rihanna went into the call of her new single "Hard": "A-yeah-yeah-yeah." The singer seemed comfortable and confident as she performed the track live for the first time.

Rihanna will perform her entire new album at a concert in London on November 16 that will be webcast live around the world.