Belly and Radiohead. Don't know 'em? Bet your daughter/kid brother/teenage neighbor does. I know, 'cause they were all there at the Riviera when the two rising baby bands played a collective 1-hour, 40 minute concert Friday night.

The show, of course, was sold-out. Not surprising, since every time you turn on one of those alternative radio stations, Belly's "Gepetto" or Radiohead's "Stop Whispering" is playing. Belly headlined, but it could have gone either way. And Radiohead fans who stayed till the end received a treat when anemic vocalist Thom Yorke joined Belly's Tanya Donelly for an acoustic encore.

Belly's played in Chicago many times this year, including a triumphant Fourth of July performance at Grant Park where the group was received better than headliner Matthew Sweet. Led by gamin singer-guitarist Donelly, Belly once again gave a fierce concert at the Riv.

Hers is a voice that is both painfully anguished and silky sweet. Swaying in black bell bottoms, Donelly's emotions were bared, singing "Would you lay your body down on the tracks for her? . . . Don't you have someone you'd die for?"

Her three bandmates provided thundering backup. Looking like one of the flaxen-haired Nelson twins and moving like she'd been weaned from Van Halen, bassist Gail Greenwood's metal male posturing was entertaining, but at times a bit much. The stoic Gorman brothers -- guitarist Tom and drummer Chris -- never spoke.

Radiohead's set was less spectacular. Yorke's voice was shot, no thanks to an in-store acoustic performance just before showtime.

The songs on the English band's debut CD "Pablo Honey" are built around feedback, chorus and kick. Songs such as the deceptively tranquil "Creep" work when Yorke is able to maneuver his voice around the whispered beginning and build in strength through the impassioned finish. But this time around, he didn't have the strength to maneuver that complicated path.

On the other hand, Jonny Greenwood's fuzzy guitar playing was authoritative, dictating the mopey melodies and complementing Ed O'Brien's rhythm guitars.