By Brian Orloff

James Iha knows a thing or two about supergroups. He was the lead guitarist for the Smashing Pumpkins, one of the most influential rock bands of the 1990s.

Since the disbanding of the Pumpkins, which Iha demurely calls "my old band," he has dabbled in solo projects, including founding a record label, Scratchie Records.

But last summer he received an invitation to join Tool frontman Maynard James Keenan's supergroup du jour, A Perfect Circle. The band, which released its second album, Thirteenth Step, in September, will play the University of South Florida Sun Dome on Friday.

"They needed a guitar player, and they just e-mailed me," Iha said by phone from Los Angeles. "I just came down and did it. They e-mailed me three weeks before they were going out on tour.

"I had two weeks rehearsal with them, and I've been on tour ever since," he added, laughing.

Iha is A Perfect Circle's latest addition, joining the band after the album was recorded. Bassist Jeordie White (formerly known as Twiggy Ramirez, Marilyn Manson's No. 2 man) stepped in for departing Paz Lenchantin. Get this: Lenchantin quit to join Zwan, the latest band of former chief Smashing Pumpkin Billy Corgan.

Despite the supergroup status of A Perfect Circle, Iha said individual egos rarely threaten the band's cohesion. Nor do they detract from the epic, sprawling music.

"It's not like Cream, where someone's doing a drum solo and there's a bass solo," Iha said. "We're all playing parts that are written out already. There is an element of, well, "Those guys played in other bands,' but it's pretty normal, I think."

For Iha, the biggest challenge was mastering the complex song structures.

"I just did a lot of practicing," he said, laughing at his understatement. "I had an intense two-week course. It's hard to learn the songs and memorize them and have them be part of your own mind. To learn someone else's musical taste and vocabulary that they use to write with can be difficult. But here I am.

"I play the way I play, but I try to follow the arrangements of the song. They've already written it, they've recorded it, and they've mixed it, so it's just kind of getting a live representation together."