MANCHESTER, TennesseeTwenty One Pilots got the Bonnaroo Music and Arts Festival revved up for a weekend of revelry with the off-the-charts pep of their opening-day set Thursday.

The genre-bending Ohio duo were clearly stoked to be performing at the festival, as singer Tyler Joseph alternately bashed his piano and excitedly sprinted across the stage — at one point, even climbing the rafters to take in the view from on top of the rigging.

Their poppy blend of hip-hop, indie rock and electronica attracted a giddy crowd, who were thrilled by their single "Holding On to You," accented by Josh Dun's pounding drums. "The Run and Go" was another favorite that had fans bopping up and down to its sing-along chorus. "House of Gold," "Ode to Sleep" and "Guns for Hands" rounded out the set.

The MTV Artist to Watch also opened the Hangout Festival in Alabama last month.

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Friday night's (June 14) Superjam will feature RZA, DJ Jazzy Jeff, Solange, Schoolboy Q and Chad Hugo of the Neptunes, supported by Boston funk band Lettuce. And, you never know who else will show up: Last year, D'Angelo made a surprise appearance during Roots drummer ?uestlove's Superjam.

Also Friday, Wu-Tang Clan, celebrating the 20th anniversary of Enter the Wu-Tang (36 Chambers), will be in full force — a very rare occurrence. Paul McCartney and Wolfgang Gartner also will perform.

For Saturday night, Bonnaroo added Jack Johnson to fill in for Mumford & Sons, who canceled their appearance after bassist Ted Dwane had surgery to remove a blood clot on his brain.

Odd Future's Earl Sweatshirt also called off his set, telling fans Thursday that he was too ill to perform. "To everyone at Bonnaroo: I'm sorry I can't make it, I'm really really f---ing sick but I will make it up to Tennessee as soon as I possibly can," Earl wrote on Twitter.

Hoping to stage a comeback, R. Kelly has a few high-profile festival gigs planned for this summer, including Saturday at Bonnaroo. In one of the weirdest cameos ever, R. Kelly joined Phoenix at Coachella in April for a mash-up of their "1901" with his "Ignition (Remix)." He has only four shows scheduled for this year. Nas and Bjork are also on tap for Saturday.

The festival will wrap up Sunday with Macklemore & Ryan Lewis, Kendrick Lamar and A$AP Rocky.

Are you at Bonnaroo 2013? Share your reviews in the comments section below!