Rehearsals for Tuesday's Billboard Music Awards got off with a bang yesterday (Dec. 4) at Las Vegas' MGM Grand Garden Arena, as Ciara's pyro-laden set kicked off a day filled with high-energy numbers.

Rehearsals for Tuesday's Billboard Music Awards got off with a bang yesterday (Dec. 4) at Las Vegas' MGM Grand Garden Arena, as Ciara's pyro-laden set kicked off a day filled with high-energy numbers. Ciara, fresh off her first night of opening for Gwen Stefani's Harajuku Lovers tour, performed a medley of her hits, including "Goodies" and "1, 2 Step."

The singer, who left BMA rehearsals for a show with Stefani in San Diego, tells Billboard.com she's confident her stint with Stefani will garner her greater exposure.

"Gwen has a totally different audience than I do and I think even with the blessing of having those big records that I've had this year, her fan base is much broader," Ciara says.

Carrie Underwood showed that she's already a pro at live performing. After only two run-throughs of "Some Hearts," she was done for the day. Underwood says she opted to sing the title cut of her Arista debut rather than current single "Jesus, Take the Wheel" since she has already performed the latter on a number of TV shows.

"We wanted to keep things fun and up-tempo," Underwood tells Billboard.com. "'Jesus, Take the Wheel' is an amazing song but I've been doing it everywhere and we wanted to try something new and see what kind of reaction we get from it."

R. Kelly ran through "Let Your Light Shine," a song he wrote for the recent Hurricane Katrina relief album "Come Together Now: Hurricane Relief." Accompanied by a string section, "praise dancers" and a 50-plus-member choir, Kelly sang the uplifting number in front of images from the tragedy.

During the BMAs, volunteers will go through the audience collecting donations for the American Red Cross, Habitat for Humanity and Musicares. More information is available at HurricaneReliefCD.org.

Among the acts rehearsing for their BMA performances today are Ashlee Simpson, Toby Keith, Stefani and Green Day.