Oh my Gaga! What a lovely, liberating, hot mess you've given us with your Monster Ball Tour.

Lady Gaga's two-hour concert Monday at the sold-out Xcel Energy Center in St. Paul was a ridiculously ambitious, delightfully decadent and lovably confusing evening of performance-art, befitting the biggest pop-culture phenom of this century.

Part pop-opera, part gay-pride rally, part self-help seminar, the conceit of the show is that Gaga, the 24-year-old New Yorker, is trying to get to the Monster Ball, the most freeing, liberating place on the planet. Alas, her cab breaks down, she and her friends take the subway, get lost on the Glitter Road somewhere in the deep, dark forest in Central Park, and finally arrive at the Monster Ball. This four-act psychodrama melds "Wizard of Oz," "Grease" and "Rocky Horror Picture Show" and somehow comes off as completely Gaga.

Aided by 11 ambisexual dancers and a band that included a string harp player, Gaga proved to be a wooden dancer and an emotionless singer. In the first half, her face was painted hopelessly expressionless, as if she stepped out of the wrong "Jerseylicious" salon that failed to color her dark roots and then gave her blonde hair garish yellow ends. Even though she was performing crowd-pleasing hits like "Just Dance" and "Lovegame," she seemed cold and impersonal, not like the friendly diva-in-waiting that she was in March 2009 at the Fine Line.

Then Gaga did one of the crassest moves in pop-concert history by pulling out a cell phone, plugging her mobile sponsor and its donation to charity (which she named), then calling a Little Monster (that's what she calls her fans) in the audience. Turns out his name was Alejandro (the name of her current hit), but he complained about her liking Fernando, too. "I like to keep my options open," Gaga retorted.

Suddenly, she transformed from frozen-faced fembot to wonderful pop star and turned "Telephone" into a fierce club banger. Then it was time to remind the 15,000 Little Monsters that beneath all the glam-tastic outfits and eye candy, there is a Grammy-winning songwriter who writes pop songs on the piano. Wearing a black Latex bikini covered with silver studs, she sat at a grand piano from which flames flared 10 feet in the air and performed "Speechless," a torchy ballad. Then she offered an unrecorded, unplanned piano ditty called "Living on the Radio," followed by "You and I," an Elton John-evoking piano rocker destined for her next album.

Perched at the piano, Gaga sang with a smile and a strong, rich voice, finally infusing her personality into her music. Thereafter, she was on fire, tearing through a royal flush of hits, including "Poker Face," "Paparazzi" and "Bad Romance."

Wearing a parade of outlandish outfits inspired by great architects and quirky filmmakers, Gaga proved to be the pied piper of weirdness, waving the freak flag for all misfits, outsiders and lonely hearts. She has a license to offend because she preaches tolerance, and her fans give her rope.

If she opted for more of herself instead of the self-conscious weirdness, the Monster Ball would make Madonna's recent tour look like a dance recital, Beyonce's like a Broadway burlesque revue and Britney Spears' like a Pussycat Dolls rehearsal. In other words, the Monster Ball has the potential to be the biggest pop monster tour of them all.