Roots Picnic / June 5, 2010 / Philadelphia (Festival Pier at Penn's Landing)

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?uestlove of the Roots performs at the 3rd Annual Roots Picnic at the Festival Pier on June 5, 2010 in Philadelphia, Pennsylvania.

In only its third year, the Roots Picnic has established itself as Philadelphia's premiere outdoor summer festival thanks to a mix-and-match collection of bands and relaxed atmosphere. Although a few aggravating scheduling problems threatened the easygoing vibe, Saturday's show at Philly's Festival Pier contained energetic sets, memorable collaborations and a crowd that was more than ready to dance the sweltering heat away.

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Classic hip-hop once again defined the event, with the Roots performing alongside members of the Wu-Tang Clan and DJ Diamond Kuts spinning old-school rap tracks between sets. However, the early afternoon included a more eclectic lineup than the past two years.

After indie-folk artist tUnE-yArDs created songs out of an abrasive mix of chopped vocal samples, the Foreign Exchange trotted out a smooth set of jazzy R&B. Nigerian-born soul singer Nneka showed off her beautifully tinny voice on songs like "The Uncomfortable Truth" and "Suffri," while Philly rapper Meek Mill rocked the side stage with minor hit "Make 'Em Say" before exiting after barely 15 minutes. Unfortunately, the schedule of the side stage became disjointed early in the day, and bands frequently hit the stage nowhere near their allotted time.

An early highlight came from South African duo the Very Best, which brought two backup dancers and a celebratory mood to the main stage. Following a tribal jam that riffed on Yeasayer's "Ambling Alp," the group made the audience bounce along to its shimmering single, "Warm Heart of Africa." "You know South Africa's gonna kick your ass in the World Cup, right?" frontman Esau Mwamwaya playfully asked the crowd, which responded with a chorus of boos and "U-S-A!" chants.

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As the humidity finally began to dip, Mayer Hawthorne and the County breezed through a set that included their finger-snapping track "Your Easy Lovin' Ain't Pleasin' Nothin'" and a cover of ELO's "Mr. Blue Sky". When the set concluded, the crowd rushed over to the side stage to catch the first-ever collaboration between Roots drummer Ahmir "?uestlove" Thompson and veteran beatmaker DJ Jazzy Jeff. The two Philadelphia hip-hop icons immediately developed a rapport, with ?uestlove providing head-nodding percussion while Jeff scratched on songs by Jay-Z and Dr. Dre.

Playing the main stage for over an hour and a half, the Roots' 8-piece band delighted the crowd at its own festival, with a breathless mix of live instrumentation and hard-charging rhymes courtesy of MC Black Thought. Instead of getting lost in 15-minute live jams as the band frequently does, the Roots remained focused during the set and packed songs like "Thought @ Work" and "Here I Come" with a palpable urgency.

After surprise guest John Legend accompanied the Roots for a handful of songs, the Wu-Tang Clan's most potent trio -- Ghostface Killah, Raekwon and Method Man -- graced the stage and murdered back-catalogue classics like "Bring the Pain," "C.R.E.A.M." and "Criminology". Although this year's festival was denied the presumed headlining performance by Run-D.M.C., the raised W's and "Wu-Tang" chants showed that the crowd was not disappointed with the group's replacement.

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Due to the problems with the side stage schedule, Bajah & the Dry Eye Crew's performance was scrapped, and Virginia rap duo Clipse took the stage three and a half hours after originally scheduled to perform. Pusha T and Malice pummeled the crowd with their intense street rap before the opening melody of Vampire Weekend's "White Sky" bellowed from the main stage. "I don't like that shit, man," a visibly angry Pusha T said about the scheduling conflict before capping the set with "Popular Demand (Popeye's)".

The crowd poured out to catch the rest of Vampire Weekend, who provided a much-needed comedown from the intensity of the Wu-Tang Clan and Clipse. With perfect summertime anthems like "Holiday" and "Oxford Comma" echoing into the night, the indie-pop band captured the looseness of the Roots Picnic festival and closed out another successful year.