SAN FRANCISCO -- The Cardigans tried on a new sound at the Slim's nightclub here Sunday. It seemed a perfect fit.

"This [show] is an appetizer for the February thing," statuesque singer Nina Persson said, referring to an extensive Cardigans tour planned for early next year. The gig offered a glimpse of the new musical approach the Swedish group pursued on its latest album, Gran Turismo.

The ephemeral performance -- one of only five on a current, U.S. promotional swing -- featured a darker, less bubblegummy sound than the group has been known for in the past. Setting the mood early, the Cardigans opened with "Paralyzed" (RealAudio excerpt), the new album's ominous first track, in which Persson sang about "the sweetest way to die."

Dressed in a sleeveless black shirt and black leather pants, her blond hair pulled back into a haphazard ponytail, Persson at times was downright chatty.

"This song is about all the stupid things we do," she said, referring to "Lovefool" (RealAudio except), the band's breakthrough, sunny-sounding hit from its 1996 album, First Band on the Moon.

Along with "Lovefool," the band sprinkled in a few of its other earlier -- and fluffier -- songs, such as "Been It," also from First Band on the Moon, and "Rise and Shine," from 1996's Life.

As they went about their work onstage, the Cardigans appeared to revel in surprising their fans with the exaggerated, heavy vibe of the new songs. Much of the newer material employed trip-hoppy beats and processed guitars to yield a more ambient, melancholy mood than the band's fans normally might expect.

While acting as a teaser for the Cardigans' upcoming tour, the show also gave the band a chance to convert skeptical fans to its new, less cheerful sound.

"I've been a big fan of theirs for years, and I wasn't sure about Gran Turismo when I first heard it," concert-goer Josh Rohmer commented. "But hearing some of the new songs live made me like them a lot better. The show was excellent."

The nine-song set included such Gran Turismo tracks as "Erase/Rewind," "Hang Around" and the first single, "My Favourite Game" (RealAudio excerpt).

"We're going to finish this set with a power ballad," Persson cooed before the lovely, plaintive "Higher."

Despite their moodier sound, the Cardigans obviously still have fun onstage. They performed with energy and enthusiasm, with Persson and guitarist Peter Svensson often exchanging taunting glances -- one almost expected them to start sticking their tongues out at each other.

Svensson and bassist Magnus Sveningsson took every opportunity to inject heavy, grinding guitars and powerful basslines whenever the sweeter melodies allowed.

The guitar and bass crunched loudest during "Been It" and the encore, their cover of Black Sabbath's "Sabbath Bloody Sabbath," from Life, which melted into a happy mess of over-the-top guitar machismo. As if encapsulating the band's musical evolution, the song began as light pop, turned metal toward the middle, then morphed into a groove-heavy disco tune toward the end.

"I love their new sound, especially live since it sounds even harder," concert-goer Sofia Ramirez said. "I still like their old stuff, but they're headed in a great direction."