CHICAGO -- Pearl Jam have become masters of the slow boil.

While a tornado warning was in effect outside the United Center on Monday night -- the sixth stop on the Seattle supergroup's tour that pulls into Molson Park in Barrie on Aug. 22 -- inside Eddie Vedder and company were expertly whipping up a small storm of their own.

The action built up slowly and self-assuredly over the course of a relaxed and loose, two-hour plus show that ended, oddly enough, with a cover of The Who's Baba O' Riley.

Taking the stage after a 45-minute set by former Pixie Frank Black, the boyish-looking, short-haired Vedder was all tightly wound nervous energy during the quiet show opener Long Road, which neverless had the sold-out crowd of 23,000 on their feet and screaming.

By the second song, the hard-rocking Do The Evolution, from Pearl Jam's latest album, Yield, Vedder was in full performance mode, making ape-like gestures around the stage while howling: "I'm ahead, I'm advanced, I'm the first mammal to make plans."

Vedder's theatrics -- I'm not sure but I think he was wearing nail polish, perhaps in homage to his Chicago Bulls buddy Dennis Rodman? -- must have tickled his grandmother. Yes, Marge Vedder was in the audience and attracted a crowd of young, picture-taking autograph seekers to her seat in the front row of the stands before the concert began.

Back on stage, meanwhile, Vedder was helped out considerably by the continuous guitar attack from bleached blond Mike McCready, who closed his eyes and tilted his head back during his solos, and the similarly talented, if more restrained, Stone Gossard.

Bassist Jeff Ament and former Soundgarden drummer Matt Cameron, filling in for a non-touring Jack Irons, also proved to be an energetic rhythm section with Ament charging around the stage during the No Code rocker Hail Hail, losing his trademark hat in the process.

Pearl Jam's stage setting, as has been the case in the past, was as basic as it gets, with five large flickering candles in the background against a plain backdrop onto which colored lights were projected with the occasional strobe light thrown in.

When it comes to special effects and Pearl Jam, Vedder would appear to be it.

His jubilant stage presence during such older stadium anthems as Dissident, Even Flow, Corduroy, Rearviewmirror, Jeremy, Daughter -- especially Daughter, even if Vedder had the crowd singing the first few lines from Pink Floyd's Another Brick In The Wall by the end of that song -- Alive and Better Man prompted massive singalongs and exaggerated hand gestures from the audience.

Even newer songs like Given To Fly, In Hiding and I Wish (which was accompanied by a silver disco ball) and quieter numbers like Off He Goes and Present Tense went over well.

So maybe Yield, released in February, hasn't exactly flown out of record stores. Its current sales are 200,000 copies sold in Canada, 1.6 million in the U.S. and three million worldwide.

But Pearl Jam, now in their eighth year, seem to be improving as a live act. This is a band that knows how to let things percolate for often exciting results. Their sprawling, epic-like songs don't hurt either.