Tommy Emmanuel's speech remains thick with the accent of his native Australia, but nowadays he calls the United States home.

Between stints of touring, the world-class guitarist retires to Nolensville, Tenn., just south of Nashville, where he's lived for nearly four years.

Before Emmanuel got his green card, the 55-year-old virtuoso would spend years at a time stateside on what is known as an "O-1" working visa for people with "extraordinary ability."

That kind of visa carries a burden of proof.

"You have to prove you're unique — that what you do, nobody else does," Emmanuel said in a telephone interview. "That's pretty hard in my business."

If immigration officials harbored any doubts about his ability, they could have consulted country guitar legend Chet Atkins, Emmanuel's mentor and friend. The late Atkins referred to Emmanuel as the greatest fingerpicker in the world.

If that didn't satisfy them, they could have knocked on Eric Clapton's door. Clapton, a rock-'n'-roll icon whose name appears in permanent ink on the shortlist of the greatest guitarists of all time, once called Emmanuel the best guitarist he'd ever seen.

As testimonials go, those aren't too shabby.

For an independent assessment, check out Emmanuel on Sunday, July 25, when he performs at the Whitaker Center in Harrisburg.

The two-time Grammy nominee plays with a dexterity that defies the limits of two arms and 10 fingers, and he demands a flexibility from his instrument that a standard guitar man wouldn't even consider. In his hands, a six-string acoustic must at once play lead, bass and percussion. He beats, bends, plucks, scrapes and, of course, picks his guitar as if he were trying to shape it into something better suited to his musical purpose. With their many scuffs and patches of worn-off varnish, his favorite guitars look as if they've been run over by a van a few times.

Despite the physicality of his performance, Emmanuel never strains; he just plays hard.

"Les Paul told me years and years ago — he said, 'The most important thing when you're playing is to fly your kite. See how high you can get it.' Just really go for it and be afraid of nothing."

Emmanuel's kite soars to lofty heights in such numbers as "Classical Gas," an amped up version of the Mason Williams instrumental, and various fret-fortified adaptations of classics from Jimi Hendrix to the Beatles.

It's probably a little easier to play without fear when you've learned from the greatest. Emmanuel's innate talent inevitably led him away from his native Australia, where he had been performing professionally since he was a child. On the road, he had the good fortune to meet and forge personal relationships with nearly all of his guitar heroes: Les Paul, Jerry Reed, Duane Eddy, Hank Marvin (of the Shadows) and Atkins, whose records were his primers as a child.

In 1997, Emmanuel and Atkins released an album together, "The Day Finger Pickers Took Over the World." It would be the last album for Atkins, who died in 2001. Before his death, Atkins made Emmanuel promise that he would dedicate his life to sustaining the music they both loved.

He takes that charge seriously.

"Reaching out to the younger generation is the most important job that I know," said Emmanuel, who will soon go live with "Tommy TV," an Internet-based insider's guide to his music, with downloadable instruction and commentary.

Emmanuel can't handle a computer with the same facility he brings to the guitar, but he keeps people around him who know how to broadcast his message. Given his immense talent, that message had been spreading on the Internet for a while before he got wind of it.

He tells this story:

"Years ago, my agent in Holland rang me and said, 'Can we do a second show in Sweden, in Stockholm?' He said the first one sold out. And I said, 'I've never been there before. How is that possible?' ... So we did two shows in one night. And when I got there, I was talking to a guy backstage, and I asked him, 'How do all these people know about me?' and he said, 'We watch you on YouTube.'"

Indeed, Emmanuel's performance videos have elicited many millions of views on YouTube, and in each video the only thing more apparent than his virtuosity is his frame of mind: He's genuinely happy.

"I'm absolutely having the time of my life," he said.

Tommy Emmanuel will perform at 7 p.m. Sunday, July 25, at the Whitaker Center's Sunoco Performance Theater in Harrisburg. For ticket information, call 214-2787 or visit whitakercenter.org.