BERKELEY, Calif. — Close your eyes when Corey Harris picks his acoustic guitar, and you might think the ghost of Robert Johnson or Lightnin' Hopkins was in the house.

The up-and-coming country-blues artist's raw, low-down finger-picking brings to mind the rural, back-porch songs of Texas and Mississippi.

But just when you figure the tall, dreadlocked character is strictly a bluesman, he plays a light-hearted Jamaican or calypso tune, or even a rhumba.

No boundaries. He doesn't mind starting a blues song with a romantic flamenco riff either.

Still, Harris always returned to his primitive blues roots Wednesday night as the opening act for Tracy Chapman at the Berkeley Community Theater.

"In spite of this Gold Rush, dot-com economy, some people still pick cotton for a living," he drawled to the audience as an intro to his original song "King Cotton."

"Some still pickin' cotton, some still pullin' corn, workin' with their best suit on."

On a Son House song, "Preachin' Blues," his jangling guitar sound and raw phrasing roused quite a few Chapman fans in the crowd.

Harris also has an edge, from the way he drives his picking fingers through the strings on the hard beats to the mean slide he delivers on his National steel guitar on a tune that he soon transforms into a gospel song called "Did My Lord Deliver Daniel."

Harris also takes a page from old country-blues masters when he calls

out to his guitar: "Tell 'em what you said," and then plays a response

lick mimicking his vocals.

Harris has a powerful, gutsy voice that belies his age — he's 30. Perhaps the time he spent singing on the streets of New Orleans' French Quarter is what gives it its maturity.

He does some hooting and shouting reminiscent of old-time blues, too.

"The guy's really soulful and bluesy for a younger guy, and he seems like he's got the staying power to be around a long time," an obviously impressed Jerry Beckman said.

Harris delivered a taste of his new Alligator Records album, Greens from the Garden (RealAudio excerpt of "Introduction to the Greens"), with his own haunting, down-home song "Lynch Blues."

"What do I see hanging beneath the trees/ Well they'll wanna hang you, if you don't bend at the knees.''

Harris, currently living in Virginia, seems to have a little Taj Mahal in him, too, and doesn't mind playing the real oldies such as Memphis Minnie's "Bumble Bee Blues."

He recently collaborated with Louisiana's

COLOR="#003163">Henry Butler, a blind piano player, on their

album vu-du mentz, a re-working of "Voodoo mens."

Harris will continue playing as the opening act for Chapman on her upcoming European tour.