LOS ANGELES -- As soon as the

curtain opened at the House of Blues on Wednesday night, fans who'd come to see post-modern roots-rockers Cracker perform knew they were getting more than they had counted on.

Standing center stage behind the curtain was Counting Crows vocalist Adam Duritz, welcoming them to the show. And on the right side of the stage was blues-pop songstress Joan Osborne, ready to back up Cracker frontman David Lowery with her powerful, soul-mama voice.

"I had no idea they were going to be here," 22-year-old concert-goer Courtney Herr said. "As soon as the show started, I was like, 'That's Adam Duritz and Joan Osborne!' But my friend was like, 'No, it isn't.' I knew it was, so we bet a beer on it. She asked one of the door guys. I won."

The show -- the first of a two-night Cracker stand at the venue -- featured Duritz and Osborne on several songs, contributing to the show's many standout moments. But even when the guest singers weren't onstage performing, they could be seen sitting down on the side of the stage, singing along with Lowery.

During "100 Flower Power Maximum," folk-rocker Duritz, who was clad in a brown, button-down shirt and black jeans, looked like he was having the most fun in the house. He sat on the floor on the right side of the stage, thrashing his head and singing along.

"That was a great show," an enthusiastic Duritz said afterward. "Really a lot of fun." The singer added that Counting Crows' next album, which is being co-produced by Lowery, is almost completed.

"I love it; it's beautiful," Duritz said, referring to his band's new music. Counting Crows guitarist Dan Vickrey was also on hand at the House of Blues for a few songs Wednesday.

With his expressive delivery, Berkeley, Calif.-transplant Duritz settled easily into the leader position for a few numbers.

Osborne's sultry blues ballad featured Cracker frontman Johnny Hickman responding to her vocal with sweltering guitar wails. Wearing tight black pants and a pink sweater over a white tank top, Osborne -- who made a guest appearance on Cracker's third album, The Golden Age -- steamed up the House with her sensual style and gravelly voice.

"Joan Osborne has the most seductive voice," fan Brian Sacks, 27, said afterward. "I was aroused."

Apparently, Hickman was similarly affected. "He's all disoriented and sh--," cracked Lowery, referring to Hickman after Osborne had sashayed off the stage.

Hickman, who wore a fluorescent green shirt

and black jeans, also took the lead mic a few

times. He sang the hillbilly rocker "Lonesome

Johnny Blues" (off 1993's Kerosene

Hat) and a new ballad called "Hold of

Myself." The latter song is a number off the

soundtrack to the upcoming feature film "River Red," which co-stars Lowery. (The film opens in New York and Los Angeles on Nov. 13, with wider release to follow.)

Cracker played a great deal of material from their latest release, Gentleman's Blues, including "I Want Out of the Circus" (RealAudio excerpt) and the album's blues-ballad title track, "Gentleman's Blues" (RealAudio excerpt).

The Kerosene Hat song "Eurotrash Girl" (RealAudio excerpt) -- which featured Kenny Margolis on accordion -- inspired a sing-along response from the crowd. But Lowery was perturbed at the number of patrons talking during the performance and at one man who was throwing coins at the band throughout the show.

Before closing the main set with Cracker's 1993 smash-hit, "Low," Lowery went off on the culprits. "You know, we don't have to play L.A.," he said, obviously miffed. "There's a lot more of the country. We don't have to play here."

"The thing about L.A. is that you pay for these people to come to your show," he continued, referring to the bulky industry-guest lists that typically go along with playing Tinseltown. "It's so f---ing weird."

When the band launched into the intro to "Low," Lowery stopped again, adding sarcastically, "I know, L.A.'s sophisticated. It's a big city. But you just want to hear the hits."

For some fans, it spoiled the show.

"I thought it really sucked that he went off that way," said concert-goer Brian Sacks, 27. "It was a good crowd for Los Angeles. That just brought everyone else down."

Others said Lowery's brief tantrum was justified.

"It f---ing needed to be said!" concert-goer

Denise Rhoades moaned. "No incredibly awesome rock band and their incredibly awesome guests should have to put up with that."