The Roots and Common have come a long way since 1997. That's when Philly's sons of hip-hop began working with Common, the socially conscious MC from Chicago, on a series of jazzy rap manifestos and collaborations. That includes the Roots' Things Fall Apart of 1999 and Common's 2000 release, Like Water for Chocolate, seminal albums that established the two acts as arbiters of adventurous sound.

Now both are part of the pop-cultural firmament - ambassadors, even - the Roots as the house band of late-night TV's highest-rated program, The Tonight Show with Jimmy Fallon, the other an Academy Award-decorated composer/performer for his work on the 2014 film Selma.

It was fascinating, then, to watch the Roots and Common do an old-fashioned joint throw-down at Atlantic City's Borgata Casino on Sunday.

The Roots' show was split into two sets, with Common's hour-long set nestled in between. The Roots painted a portrait of an ensemble in transition, not quite the mighty soul-jam band of the Roots Picnic and not quite the pop-hop orchestra of Fallon's Tonight Show.

The band made long, deep references to both James Brown as funk history (the hypnotic grooves and cheerleader-ish vibes of "I Know You Got Soul") and Drake as current pop-cult (guitarist Kirk Douglas' breezy scatting of "Hotline Bling"). As usual, the band connected the dots between past and present. Drummer Questlove's in-the-pocket rhythms and Kamal Gray's impressive piano work were the musical highlights. The night's party may have been slowed by a tired Borgata Event Center crowd (not a dancing, grooving audience) and the necessity of a smooth transition into Common's set.

Still, Black Thought did everything in his power to rouse. The rough-hewn rapper led the horn-infused Roots through the aggressively punkish likes of "Section" and "The Next Movement," the latter with a soft Steely Dan-esque break. The chill from hot to cool left room for a special guest, Germantown's own Bilal, to do his usual vocal blend of creamy lover-man and high-pitched primal screamer during an intense version of John Lennon's "Mother." While Bilal howled, Black Thought jumped in, rapping about missing his own mother, who died during his childhood. Easily, this was the night's crowning moment.

Black Thought's segue into Common's set was their energetic joint number "Act Too (Love of my Life)." But the Chicago rapper - or his material - seemed stiff in comparison to the Roots' flexible bounce. His flinty voice was handsome and his messages clear-cut and on-point (especially the stoic "U. Black Maybe" and the epic "Glory"), but Common's stilted set slowed the night's proceedings. Only the J.Dilla-dedicated "Thelonious" and the gloriously rousing "The Light" caught fire, leaving the suggestion that, if he wants to do real rap again, Common should step away from acting and back into the studio.