There’s a concert recording of Elvis Presley playing in Las Vegas in 1973 in which he does something remarkable: He launches into “Hound Dog,” one of his earliest blockbusters, but instead of giving it the familiar 1956 rhythm-and-blues-style treatment, he sings it completely differently, back-phrasing it over a funk vamp inspired by Motown and Southern swamp rock. The point isn’t that the new treatment is better, but that it shows that Elvis, at this late stage in his career (though he was only 38) had the capacity to experiment and grow as an artist. He had the restless nature not to leave well enough alone, and was motivated to retool his signature works, the way Frank Sinatra did with “All or Nothing at All” and John Coltrane did with “My Favorite Things.”

The great barrier between rock and jazz is not just one of rhythm, harmony, and instrumentation, but the concept of interpretation. That’s the meat of the matter that separates rock-oriented pop from jazz and pop that’s based on the Great American Songbook. Rock hinges on the idea that there is only one definitive version of any given song, usually by the guy who wrote it. All other performances of the song are not interpretations, as they are in the world of Sinatra and Coltrane, but mere covers.

Interestingly, 2007 may be remembered as the year in which more jazz musicians than ever made efforts to break down these boundaries. In only the past few months, we’ve discussed in these pages albums by jazz musicians addressing the music of Bob Dylan, the Beatles, and, most recently, Herbie Hancock’s magnum Joni Mitchell opus. Now, you can add Elvis Presley and Elton John to the list of rock icons whose work has been retooled for jazz purposes.

There have been jazz tributes to everyone from President Kennedy to Burt Bacharach. But until now, no jazz project has gone directly into the heart of rock ‘n’ roll and addressed the canon of the music’s single most dynamic and central figure, the King himself (and I don’t mean Oliver, Nat Cole, or Benny Goodman). Pianist Cyrus Chestnut’s new album, “Cyrus Plays Elvis,” is the first full-length homage (that I know of) by a major jazz artist to the man who almost single-handedly affected the greatest sea change in all of American pop.

As a Southern musician whose playing is immersed in gospel, blues, and soul, Mr. Chestnut is a likely candidate to reinterpret Presley’s catalog, from early breakthroughs like “Don’t Be Cruel” to such mature statements as “Suspicious Minds” and “In the Ghetto.” What’s commendable is that Mr. Chestnut doesn’t feel the need to get all downtown and weird on us — he puts his personal stamp on the material while staying true to the spirit of the originals. “Minds” is still a dance-driven vamp with a minor undercurrent that mirrors the message of the text; “Ghetto” is a slow, somber ballad with a spiritual message — even the way the title phrase repeats itself suggests a church choir.

The only track I find myself skipping on replays is “Can’t Help Falling in Love,” on which Mark Gross’s soprano saxophone makes the whole thing sound like smooth jazz. Conversely, on “Don’t” (a comparatively lesser known Leiber-Stoller-Presley hit from 1957), Mr. Gross perfectly captures the cadences of Presley’s voice on his alto. The most abstract treatment is “Heartbreak Hotel,” which has a grandly Asian opening, almost like “A Love Supreme,” leading into Presley’s darkest and scariest blues, an altogether fitting visit to an establishment that the lyrics describe as a sort of roach motel for human souls. The package opens with an elemental treatment of “Hound Dog” that, although it sounds nothing like Presley’s 1973 revision, also returns the Leiber-Stoller song to its deep blues roots, and contrastingly, ends with a moving solo treatment of “How Great Thou Art,” which shows that the great gospel standards mean as much to Mr. Chestnut as they did to Presley.

“Cyrus Plays Elvis” sounds like instrumental jazz produced by a mindset similar to Presley’s, rooted in blues and dance rhythms. “Your Songs: The Music of Elton John,” by the quartet of Italian saxist Pietro Tonolo, keyboardist Gil Goldstein, electric bassist Steve Swallow, and drummer Paul Motian, is an altogether more Martian, though no less respectful, reinterpretation of the songs of the 1970s pop icon. On the whole, the feeling is similar to the melodic yet spacey trio that Mr. Motian has led for many years with Joe Lovano and Bill Frisell. The quartet’s “Rocket Man,” for instance, is in the same tempo as the original 1972 version and includes the entire melody, but the feel and the groove are so different that even a casual listener who knew the original well might not be able to recognize the tune on a blindfold test. “Goodbye Yellow Brick Road” is taken at a faster tempo, but because Mr. John’s melody was stronger here, the whole performance seems more direct.

I prefer the quartet’s versions in at least a few cases — the melody of “The One” sounds better without the cheesy ocean effects and the disco drum machinery on the 1992 original. The most memorable tune is no surprise: The ballad “Sorry Seems To Be the Hardest Word” is the rare Elton John song that was already performed by Jimmy Scott, Ray Charles, and even Sinatra, and is played here slightly faster and punchier than I expected. The Pietro Quartet confirms that it’s a song worthy of being in the jazz repertoire.

In an online promotional video for “Your Song,” Mr. Tonolo relates that when he informed Mr. Swallow of the idea behind this project, the bassist (whose fender playing in the higher register often sounds like a guitar) responded, “Oh, I actually like some of Elton John’s songs — but don’t tell anybody!” As “Cyrus Plays Elvis” and “Your Songs” prove, fans of this music don’t have to keep it a secret: The best tunes by rock-era songwriters are worthy of sitting at the big table with the grown-ups.

Mr. Chestnut will appear for a free performance tomorrow J&R Music World; Thursday, with his remarkable supergroup Manhattan Trinity, in a rare stateside appearance at Highlights in Jazz, Tribeca Performing Arts Center; and Saturday, when he’ll play the Presley repertoire in a special concert with his working trio at Miller Theatre, at Columbia University.

wfriedwald@nysun.com