A Perfect Circle are a big tease. The band proved as much in the opening minutes of their sold-out show a week ago Thursday at Brandeis University in Waltham when sultry violinist Paz Lenchantin emerged under a lone spotlight and swayed her hips as she played the Eastern-sounding opening to “Renholder.” That was more than enough to get the crowd going until the rest of the group joined in, which they soon did — minus singer Maynard James Keenan. Where was Maynard? As “Renholder” bled into the rocking “Thinking of You,” he finally wandered on stage in a pair of tight leather pants and nothing else. The crowd went bonkers.

The surprise emergence of A Perfect Circle as one of art metal’s leading lights has all been a big tease, of course, and the moment of truth — the imminent release of the long-awaited third album by Maynard’s other band, Tool — is suddenly just two months away. So fans at last week’s show were faced with the odd prospect of saying farewell (for the time being, at least) to what’s essentially a new outfit at the height of its success. But the mood was one of celebration, not grief, and the group turned in an enthralling 75-minute performance that delved into almost every dark corner of their dense debut disc, Mer de Noms (Virgin).

The highlight came only four songs in with a dramatic recasting of the hit ballad “3 Libras.” “We’re gonna have some fun,“ announced Maynard, and the band launched into an echoing, feedback-laced electric interpretation of the song that eventually melted into the original. Songwriter/guitarist Billy Howerdel led his bandmates into all kinds of Radiohead-style psychedelic explorations. Maynard made recurring jokes about drummer Josh Freese and sang his balls off all night. He stripped down to a pair of black briefs for the end of the set, leaving the satisfied crowd with steamy versions of the hits “Judith” and “The Hollow.”

Boston underground rock heroes Cave In met the masses in a big way with their half-hour opening set. Guitarists Stephen Brodsky and Adam McGrath got the crowd’s attention right off the bat by attacking their instruments with toy rayguns on the opening “Decay of the Delay,” a spacy instrumental from the band’s recent OK Computer–style metal opus, Jupiter (Hydrahead). Most of that album followed, with mercifully little heckling from the crowd. Brodsky’s between-song mumbling was tough to make out, but the guys were in fine arena-rock form by the time the set closed with the metallic “Big Riff,” launching their rayguns and water bottles into the fray.