NEW YORK — "Doctor Funk? Hello. There's this red-bearded white guy from Vermont down here. Says he's got a vicious funk infection. Says he oughtta be able to hang with you."

For a few hours at the Roseland Ballroom on Friday, guitarist and Phish frontman Trey Anastasio, armed with a few of his northern Vermont cronies, made a pretty convincing case for such an honorary funk degree.

Flanked by a familiar, groove-friendly rhythm section (bassist Tony Markellis and drummer Russell Lawton) and an adept horn section (saxophonist Dave Grippo, trumpeter Jennifer Hartswick and trombonist Andy Moroz), Anastasio waded though two generous sets, mixing funky originals with covers from across the Americana spectrum for an adoring sold-out crowd and referencing everyone from the Talking Heads to Professor Longhair along the way.

True, for every awe-inspiring moment — such as the 20-minute, disco-tinged ambient exploration of Anastasio's "Gotta Jiboo," which veered in and out of a dizzying circular progression created by intersecting guitar loops — there were those that provided little more than variety, such as the energy-deflating, solo acoustic rendering of "Back on the Train" and Anastasio's perfunctory reading of the Band's "It Makes No Difference."

But the band's ability to lock tightly into Anastasio's bubbly groove vehicles, coupled with Anastasio's genuine desire to push the good-times vibe made any of the evening's musical shortcomings seem rather transparent. The normally jovial Anastasio was downright giddy at times, smiling and pumping his fist during the horn solos, bouncing back and forth and barking out on-the-fly instructions to his crew.

The horn section's brassy groundswells breathed new life into the slow-burning, cowbell funk of "The Way I Feel," played during Anastasio's first solo tour (with Anastasio backed by Markellis and Lawton in the power-trio format) and featured on his 1998 experimental album, One Man's Trash. Horns also were the driving force behind an enjoyable new punk/ska number with the working title "Burlap Sack and Pumps."

But the key to the evening's funk was the one-two punch of Markellis and Lawton, who deftly anchored the band's grooves with gutsy yet simple precision, allowing Anastasio and company to hover above the low end, weaving colors and textures at will.

For his part, Anastasio worked well as a party-band frontman, exhibiting a surprisingly strong vocal range during solid covers of Bob Marley's "Mellow Mood," and Bob Dylan's "Rainy Day Women #12 & 35," predictably among the evening's crowd favorites. But it was during the band's extended instrumental improvisations — founded on his own looping effects and the band's repeating rhythmic patterns — that Anastasio truly drew fire. On "Sand," Anastasio allowed his trademark intersecting delayed guitar loops to hang, turned to his adjacent keyboard and began to tinker away like a club-seasoned knob-turner while the green-lit dance floor soaked up the band's demented, techno-bent beats for over 15 minutes.

The tour is Anastasio's second official Phish-less trek of his career, but with Phish on an indefinite hiatus — the first in the band's 17-year history — the show took on an almost cerebral meaning for some fans, a fact Anastasio did not hesitate to address.

"I will not forget where all this energy is coming from and where we came from," Anastasio said. "You are the essence of this whole thing, and I will do my best to keep everything going."

Before the evening drew to a close, Anastasio summoned Phish keyboardist Page McConnell to the stage for "First Tube," a song written by Anastasio for a 1998 one-off with Markellis and Lawton under the name 8-Foot Fluorescent Tubes. McConnell, beer in hand, added syncopated keyboard riffs to the raucous rendition.

McConnell returned for the band's encore, a loose, guitar-led romp through Billy Preston's R&B shuffle "Will It Go Round in Circles." It was a fitting close to what was essentially a therapeutic show for the Phish deprived: fans hoping Anastasio and McConnell will come full circle and the band will soon re-form in earnest.

Anastasio, though, just seemed content to be where the funk is.