When guitarist Lonnie Mack scored a Top Five hit with an instrumental version of Chuck Berry's "Memphis" in 1963, no one was more surprised than Mack himself.

"I was on the road with a friend of mine, Troy Seals, who's a big-time songwriter in Nashville now," he explains. "He had a band and I had never worked on the road before, so I joined. I cut 'Memphis' a few days before we left and never gave it a second thought. Next thing I know the song is a hit, and instead of Troy being out in front with the band, I was out there. Funny thing, I wasn't playing many instrumentals back then, mostly songs. A friend just suggested I cut the 'Memphis' and we did." The result, says Mack, who performs tonight at Club Saba, was a string of one-nighters that's "still going on."

Although "Memphis" was his only national hit (regional hits like "Wham!" and "Chickin' Pickin' " would follow), his distinctive guitar tone, laced with vibrato, and the manner in which his phrasing alternately reflected and fused country, gospel, blues and rockabilly, influenced a subsequent generation of guitarists. At the top of the list is the young Texas blues phenom Stevie Ray Vaughan, who produced "Strike Like Lightning," Mack's first album in eight years.

Vaughan has good reason to remember buying Mack's debut "The Wham! of That Memphis Man" as a kid in the early '60s -- it was the very first album he purchased -- but the two didn't actually meet until the late '70s, when Mack went to Texas in search of musicians for a band he was forming.

"A friend told me to check Stevie out when I was down in Austin, though we weren't really looking for a guitarist at the time," he recalls. "I thought he was great. He played my tune 'Wham!' and I knew exactly where he was coming from. You can hear his influences, but he has his own thing, too . . . . He's more influenced by [Jimi] Hendrix and by a lot of hard-core blues players than me. I get my music more from country and gospel and the whole rockabilly scene, but I really enjoyed hearing him. I wanted to produce him at a recording studio we had in the Poconos, but my partner was killed in an accident."

Although Mack's name is often linked to two of his more obvious influences -- guitarists T-Bone Walker and Merle Travis -- he gives his family and several obscure guitarists in Indiana, where he grew up, most of the credit for shaping his sound. "A guitar player named Robert Ward was the first one I ever heard use a Magnatone amp," he says. "Most amps back then had a tremolo effect, which brings their tone in and out, but the Magnatone had the vibrato effect, changing the pitch. I've been using the same effect ever since."

When it comes to singing, Mack looks mostly to blues and gospel music for inspiration, which may explain why a lot of disc jockeys originally assumed he was black. "Back then there just wasn't that many of us singing that way," he says.

He says he never felt any real pressure to duplicate the success of "Memphis," since he was recording for a tiny label owned by a close friend. He stayed with Fraternity until moving to Elektra in the mid-'60s, where he eventually became an A&R man and occasionally played on sessions with other artists, including the Doors.

"After a while I found out I wasn't playing nearly enough music to satisfy me," Mack says. "So I headed back to Indiana and opened a music park -- played there with some friends for a couple of years." He later recorded several albums for Capitol Records before finally moving to the Austin area two years ago.

When Mack agreed to return to the studio Vaughan jumped at the chance to produce his new album, but the sessions were delayed when Mack became ill. He lost 70 pounds, dropping from his customary weight of 240. "I'd done so much drinkin' and carryin' on in my life that my body got really messed up," he says. "I was hospitalized a few times -- had to stop drinking whiskey, and now I watch what I eat."

Nevertheless, he is particularly pleased with "Strike Like Lightning," the best selling album Alligator Records has ever released.

"We talked about the direction the album should take, and Stevie and me agreed that we should go for my original sound, the kind of music I still play on the road. If the producer is real good, he knows that he's just there to make sure that nothing gets in the way, unless you're working with someone new to the business. I've been around long enough to know what I want, and Stevie wanted the same thing. We went for the groove. If you keep things simple and you get a groove going, then you've really got something."