Chan Marshall has finally burst out of her shell and become the rock star she has long been hyped to be. That, or she has quickly grown into one of rock's great poseurs.

Either way, the animated, theatrical performance that the singer/songwriter -- better known as Cat Power -- delivered Monday at First Avenue was a vast improvement over previous tours, when she would often hide behind her stringy hair and rarely make contact with the crowd.

The notoriously stage-shy and just plain awkward performer -- who reportedly sobered up and cheered up in the past year -- was a consummate entertainer Monday. It was a transformation as dramatic as Sandy's leather-clad resurrection at the end of "Grease."

Out supporting a new, mostly covers-filled album, "Jukebox," Marshall left her guitar at home and spent the night singing her heart out. She didn't just use her microphone for singing. She paced the stage with it, raised it up and down like a cheerleader's pom-poms, and clung to it as she bent over the stage monitors or writhed in equal parts pain and ecstasy.

The near-sellout crowd seemed a bit baffled by Marshall's reformation, and by the fact that her set list picked heavily from "Jukebox" and her Shortlist Music Prize-winning 2006 album, "The Greatest," but offered little else.

At times, her showy antics seemed a bit contrived, as if she was overcompensating for past shortcomings. This was especially true late in the 90-minute set when she chose a few overambitious covers, such as "At the Dark End of the Street" and the show-closer "I've Been Loving You Too Long."

But at least Marshall, 36, had good reason to be so invested in the music. Her band for this tour, the so-called Dirty Delta Blues Band, was nothing short of superb. Drummer Jim White (from Aussie band the Dirty Three) looked like a punk-rock Buddy Rich as he brushed or pounded his kit to match Marshall's fluctuating moods, while guitarist Judah Bauer (ex-Jon Spencer Blues Explosion) deftly reinvented soul legend Steve Cropper's gritty vibe.

A smoky, haunting version of Billie Holiday's "Don't Explain" opened the concert, followed by a rousing and climactic rendering of Janis Joplin's "Woman Left Lonely." Mid-show highlights included re-imagined interpretations of Patsy Cline's "She's Got You" and James Brown's "Lost Somebody," both showcasing Marshall's raspy but elegant singing -- which was flawless all night.

If pouring herself into her vocals was the point of her 180-degree turn as a stage performer, then call it a success. If she did it to better impress audiences, though, the verdict remains to be seen.

Chris Riemenschneider • 612-673-4658