Venerable L.A. guitar shop McCabe's has seen more than its share of highlights over the years, with Bruce Springsteen, Tom Waits, Elvis Costello and Cat Power among the artists who've graced the stage in the back of the guitar shop. Add another to that list as 150 lucky fans on Saturday night got, what the evening's performer J.J. Cale called, "a real big treat" in the form of Tom Petty and Mike Campbell of the Heartbreakers.

Cale, the veteran Oklahoma singer/songwriter, was playing the second of his two sold-out shows in the tiny room when halfway through the set, he brought out Petty and Campbell for a couple of songs.

>"They were across the street drinking, I went over to drink with them, said, 'I'm playing across the street,' and here they are," Cale told the crowd. What no one knew though was that a couple of songs would turn into half the set. After engaging in a sing-along version of 'Crazy Mama' and then 'After Midnight,' featuring a sterling Campbell solo, Cale told another story as way of introduction.

"We were sitting backstage talking and I said, 'Tom, you want to sing one?'" Cale said. Petty picked 'I'd Like to Love You, Baby,' which Cale said created one problem. "I'd never played it live and I told him, 'I don't remember it.' Tom said, 'I'll show you.' So if you can believe it, Tom Petty was backstage showing me one of my songs," Cale said, laughing.

Petty sat next to Cale, who played with ease as he wove stories throughout his delivery of blues and rock with sublime grace. It made it easy to understand why even a big star like Petty seemed suitably humbled to be up there alongside Cale.