“It’s Friday night in the Big Apple, and there are three banjos on stage,” joked Ketch Secor of Old Crow Medicine Show midway through the band’s opening set. On Friday night, Old Crow Medicine Show and the Avett Brothers took over the Barclays Center for a night of open-hearted sing-along and Brooklyn banjo reverence. The oversized hoedown was both an overdue climax and a tentative test for the two Southern bands, who have each spent the last half decade steadily carving out their own Americana pop subgenre. Would the two primarily acoustic acts be able to sustain and entertain a rowdy Friday night arena crowd for a whole night?

By the time the Avett Brothers were barely halfway through their main set, when Scott Avett sang the opening words to long-time fan favorite “Laundry Room,” any doubts of whether the North Carolina group were ready for the big stage were shattered. “Laundry Room” was just one of several moments when the band, which now has up to six members on stage, had complete control over the nearly sold out crowd at the Barclays Center. The Avett Brothers are now a welcoming, flexible pop act, attracting older hardcore country/bluegrass fans, middle aged rock & roll diehards, and young, pop lovers whose main foray into traditional music may be through Mumford & Sons, all the same.

The Avett’s showed some trepidation early in their two-hour headlining set, relying on some of their earliest, most reliable barnburners like “Colorshow” and “Talk on Indolence” to open their show. The effort was palpable, perhaps too much so, as the band overworked early on to gain the crowd’s full attention. “Bluegrass on crack” was how one nearby concert-goer who had never heard a note of the Avett’s music before Friday night, put it.

It wasn’t until the Avett’s covered country-pop pioneer John Denver’s “Thank God I’m A Country Boy,” giving the Brooklyn crowd their first true dosage of rural escapism of the night, that the Avett’s performance began to truly lock into place. The remainder of the group’s main set leaned heavily on their three most recent Rick Rubin albums, with the most attention being given to their 2009 major label breakthrough I and Love and You.

By the time the band reached “Kick Drum Heart” – the most straightforwardly catchy single from that record – the Avetts had transformed into full-fledged rock superstars, with a crowd clapping along in unison as if the song were an arena standard like “Born to Run.” The band continued to head bang and electric-guitar-solo their way through the last few songs of their set. During moments like “Vanity,” which came just two songs later, the band’s arena theatrics (and sound) owed much more to Zeppelin and Green Day than the Carter Family. By the fitting set closer “I and Love and You,” the group briefly became outright superstars during the feel good sing-along.

Seth Avett’s signature song “Ballad of Love and Hate,” which he sang alone earlier in the night with just an acoustic guitar, provided one of the evening’s most intimate  musical moments. The other highlights in the set, “Head Full of Doubt/Road Full of Promise” and “Live and Die” went over so well with the crowd that it seemed a wonder it took this long for the Avett Brothers to reach arena stardom.

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Both the Avett Brothers and Old Crow Medicine Show were mostly proud to display their mainstream pop-bluegrass success friday night. Sometimes, the main reason a group like Old Crow Medicine Show is allowed to crossover is because it wants to. Nevertheless, Old Crow Medicine Show were humble and precocious in such grand settings. Front man Ketch Secor dealt with the unlikely occasion by making half-nervous references to New York City in between songs. Their mid set climax of  “I Hear Them All,” which segued briefly into “This Land is Your Land,” was a mid-set highlight.

Old Crow Medicine Show’s performance provided a hearty traditionalist backbone for the evening, with straightforward bluegrass originals like “Humdinger” and “Alabama High Test” starting off the evening of music. The group ended their forty minute opening set, however, with an easy fitting, crowd pleasing adaptation of Tom Petty’s “American Girl,” a preview of sorts of the subsequent  genre-defying set from the Avetts.

It was telling that the Avett Brothers and Old Crow Medicine Show chose to stage their folksy arena coup at the Barclays Center, rather than Madison Square Garden. Indeed, the Avett Brothers, who have built their career off their own highly stylized idea of the back country hoedown, were a perfect fit for the Barclays, the singular emblem of the  whiskey-loving, beard and banjo-donning 21st century Brooklyn gentrification. “I’m a big banjo fan” was a line overheard, and surely uttered by many, from the adoring crowd before a note of music had even been played Friday evening. “Brooklyn, Brooklyn, take me in,” Scott Avett sang to a rapturous applause during “I and Love and You,” as if the five year old song was written specifically to one day be performed at Barclays.

Both groups spent the evening walking the line between their rigid traditional roots and their more flexible, commercial success. Just a few songs before the Petty cover, Old Crow Medicine Show performed their well known cover of the blues standard “C.C. Rider.” When Seth and Scott Avett weren’t covering John Denver, they were playing age-old instrumental traditionals like “Old Joe Clark” or putting their own melodramatic spin on “Roving Gambler.”

Both bands made a definitive parting statement, however, during the show’s encore, when the Avett Brothers invited all of Old Crow Medicine Show back on stage. The highlight of the encore was the ensemble’s performance of the Carter Family standard “Will the Circle Be Unbroken.” After the rousing cover the bands then led into the a cover of the 50’s doo-wop classic “Goodnite, Sweetheart, Goodnite.” The tried and true covers in the encore were a grateful gesture of humility on a night, and a monumentally large tour, that ran the risk of overreaching and self aggrandizing. “Will the circle be unbroken” they sang, and in so doing they answered their own question.

Setlist for The Avett Brothers @ Barclays Center in Brooklyn

John Brown’s Dream (traditional)
Colorshow
Talk On Indolence
Down With The Shine
Thank God I’m A Country Boy (John Denver)
Morning Song
Skin and Bones
Another Is Waiting
Live and Die
Laundry Room
Old Joe Clark (traditional)
Roving Gambler (traditional)
Head Full of Doubt/Road Full of Promise
Pretty Girl From Chile
Murder In The City
Ballad Of Love And Hate
Swept Away
Go To Sleep
Kick Drum Heart
Geraldine
Vanity
I And Love And You

Encore

Encore (With Old Crow Medicine Show):
Fireball Mail (traditional)
Will The Circle Be Unbroken
Goodnite, Sweetheart, Goodnite (The Spaniels)