Though Sleater-Kinney's roots are in the stridently punk riot grrl movement of the early '90s, the trio is now an amazing rock band, pure and not so simple. Saturday night at the sold-out Trocadero, S-K rollicked through 75 minutes of ecstatic blasts of inspiring rock and roll.

The group's brilliance comes from its balance of three equals. Corin Tucker's commanding, quivering voice - part girl-group swagger, part punk-rock force - could overwhelm, and it went from a seductive whisper to a scream in the joyous "Words and Guitar." But on songs such as "Far Away," from One Beat, it wove through Carrie Brownstein's more affected, gulping vocals for a dialogue that ratcheted up the tension and excitement.

The roles reversed with the women's guitar playing: Brownstein took most of the leads leaping and kicking as if she were Pete Townshend's little sister. But interlocked with Tucker's more punk-based playing, the guitars were often indistinguishable, especially on the extended bridge that linked "Call the Doctor" and "Dig Me Out."

Behind it all, Janet Weiss' powerful, melodic drumming made it easy to forget that there is no bass player in this band.

S-K's belief in the power of rock and roll came through as much in poppy anthems "Step Aside" and "You're No Rock 'n' Roll Fun" as in overtly political manifestos such as "Combat Rock." Its propulsive take on Springsteen's "The Promised Land" made perfect sense, since this trio also knows the path to rock salvation.

The Quails opened with a set of sloganeering funky punk, but the highly touted Yeah Yeah Yeahs canceled because of lead singer Karen O's laryngitis.