Hats Off to the Big Carnival : Dr. John and his band provide a hot prelude to Mardi Gras, delivering a show with rhythmic and visual delight.

Harry Connick Jr. was chosen to play the role of Bacchus, god of wine and revelry, in New Orleans this week, to preside over one of the biggest parades in his hometown’s Mardi Gras celebration.

Let that good-looking young smoothie aspire to godhead. If you want the embodiment of the human soul of New Orleans music, you’ll put somebody like Dr. John at the front of the parade.

The good doctor (real name: Malcolm (Mac) Rebennack) and his band were at the Rhythm Cafe on Saturday night, spreading the festivities while tuning up for their own big Mardi Gras gigs in New Orleans on Tuesday. Having seen their romping early set, one can only send out a warning and hope it reaches the Crescent City in time: New Orleans may have been spared the brunt of Hurricane Andrew, but Hurricane Mac is primed to do some serious damage.

With Mardi Gras in the offing, and with his mother and sister in the house, the versatile piano player made the funky, enlivening carnival rhythms of Fat Tuesday the heart of his show. Playing under a large chandelier that the club management had installed as its special contribution to the occasion, Dr. John and his seven-piece band delivered a show that was a rhythmic and visual delight.

A superb rhythm section, featuring drummer Freddy Staehle and a kinetic conga player, Smiley Ricks, put down those trademark loose-limbed beats that defy a listener to sit still. The horn section featured the wizened, bespectacled tenor saxophonist Alvin (Red) Tyler. A leading player on the New Orleans scene since the arrival in the 1950s of Fats Domino, Tyler blew concise but meaty solos that achieved great presence without straining. He left it to Charlie Miller, a squat little trumpeter with the excited demeanor of a merry gremlin, to provide the pyrotechnics with shrill, cackling blasts.

Almost the whole band was decked out in Mardi Gras finery, with spangled clothes or feathery headdress. The exception was Ronnie Cuber, a reserved baritone saxophone player from New York City, the only band member not from New Orleans. Maybe this is a spirit one has to grow up with.

In the middle of it all was Dr. John, looking like a costume party version of Henry VIII with his bulk, his beard, his regal gold- and silver-embroidered cape and a glittering, feathery stovepipe hat worn atop his trademark black beret.

A marvelous link in a chain of great New Orleans R&B; piano players stylistically descended from Professor Longhair, Rebennack not only offered nimble finger-dances on the keyboard but did some slow, sashaying dances across the stage, shaking his considerable booty during grand entrances and exits.

The Creolettes, a duo of beauties cum backup singers, sauntered with him while twirling parasols in the customary fashion of New Orleans revelers. The only flaw in the staging was the Creolettes’ failure to summon the enthusiasm that the music behind them deserved. The duo was somewhat stiff (maybe those skimpy, clinging bordello dresses were a little too tight) and didn’t respond robustly enough to dispel the notion that they’d been placed front and center mainly for decoration. They might have taken a cue from percussionist Ricks, an engaging showman who at one point took a parasol-twirling turn of his own across the stage and through the audience.

The Mardi Gras music was delivered in long stretches at the start and finish of the 90-minute set. “Iko Iko” was a suitably infectious opener, a New Orleans standard with a stomping, stutter-step beat. Even more exuberant was “My Indian Red,” a tribute to the black social clubs that parade on Mardi Gras as “tribes” in elaborate Indian chief’s feathers. An ebullient, swinging version of Leadbelly’s “Good Night, Irene” kept the good times rolling.

A musician with as many dimensions as Rebennack wasn’t about to fall into the trap of offering too much of one good thing. Having kicked off the party, he tenderly applied his low-down rasp to “More Than You Know,” an after-hours blues associated with Charles Brown. In the lyric, a man acknowledges he hasn’t done the best job of demonstrating the depth of his feeling for a woman he now fears may reject him. Dr. John stretched out the key chorus words “more” and “know” with an affecting quaver, perfectly playing the part of the reticent man trying to find a way to convey the extent of his love.

Next came a lush piano solo, and one supposed that Dr. John was going to burrow even more deeply into the sentimental mood he’d established. Instead, he took a surprising turn into tense, mysterious figures that introduced his voodoo-inspired cooker “Walk on Gilded Splinters.” With Ricks, guitarist Brian Stoltz and bassist David Barard emitting exotic bird cries and spooky falsetto echoes, he was off on an extended trip into dark, forbidden recesses; he capped the song with heavy chords of doom and a funereal coda.

“Such a Night” lightened the mood with brash horn interjections and a relaxed, purely playful piano stroll. After another sweet, sentimental ballad, “My Buddy,” the Mardi gras party resumed with “Goin’ Back to New Orleans,” a long workout that brought a strong Latin accent to Dr. John’s R&B;, complete with salsa conga solo from Ricks and a Santana-like guitar turn from former Neville Brothers sideman Stoltz.

Somebody ought to send the Nevilles a tape of Dr. John’s show, by the way: their performance at the Rhythm Cafe last month was only so-so by their high standards. Wonders might unfold the next time they play Orange County if they could get psyched to match this performance by their hometown buddy.

Opening band King Cotton, an R&B; group featuring a front line of four singers, plumbed the archives for jump-blues and doo-wop artifacts but failed to put across the oldest of their oldies with convincing zest. King Cotton (named after the roly-poly, gravelly voiced, red-shod bandleader) found its footing on oldies that weren’t quite that old. “Crawfish,” the Elvis Presley nugget, finally showcased the voices in an impressive light, as did two Motown-style soul numbers that closed the set.