Tom Morello and Gary Clark Jr. Rumble Rolling Stone's Rock Room

Day two of Rolling Stone's Rock Room in Austin on Saturday was shred heavy. Letting their guitars fly at La Zona Rosa were Rolling Stone/Sprint Street To Stage contest winner The Dime Store Novelist, Heartless Bastards, Hot Water Music, Devin, Gary Clark Jr. and Tom Morello, who played as his working-class superhero alias The Nightwatchman. After Heartless Bastards' set, which included the thunderous new tracks "Parted Ways" and "Simple Feeling" off the alt-rockers new album Arrow, the venue had reached capacity. Only an hour and half into the all-day party, there was a line down the block to get in.

Florida post-hardcore act Hot Water Music, who have been around since the mid-1990s and drop their eighth album Exister this May, treated the fist-pumping crowd to the new cut 'Drag My Body.'  Brooklyn-based Devin took punk back a couple decades, mashing it with rockabilly, ultimately sounding like Buddy Holly playing the Stooges.

But punk's chaotic strumming led to even more mayhem, as Austin's own Gary Clark Jr. set the place on fire, so to speak, with his electrifying set – the crowd's catcalling and applauding began before any of his tunes were over.  "I'll slow it down for ya for a moment," Clark said, letting the crowd catch their breath during the doowop-y "Please Come Home." "That's enough of that sweet business. We're going to get a bit wild in here."  Clark then crafted the bluesy guitar work of "If You Love Me Like You Say" and "Bright Lights" with his eyes closed. 

After his set, enjoying a smoke outside and being bombarded by phone-dropping groupies, Clark told Rolling Stone there were a number of reasons he played with his eyes shut. "Either I have sweat in my eye, or I get shy, or the vibe or the energy takes me to some place and I feel elevated. I just soak it in, close my eyes and go somewhere else." 

Tom Morello alternated between acoustic and electric axes throughout his final The Nightwatchman show in Austin. For the stripped-down opener "One Man Revolution," he modified the song to "… and on the streets of Austin, they know my name" (true to his lyrics, Morello made headlines the previous night when cops tried to bust up his Occupy SXSW concert). Eventually joined by the Freedom Fighter Orchestra, Morello's Rage Against the Machine roots came out on the angsty "It Begins Tonight." Morello vowed that he would play "nothing but heavy metal jams" in exchange for three minutes of supreme silence during the hollow-y "The Garden Of Gethsemane." Morello covered Bruce Springsteen's "Ghost of Tom Joad," and took a turn toward celtic-punk with "The Road I Must Travel," into which he threw a RATM riff at the end that sent the whole room into a moshpit.

"This is our last show at SXSW, so we have nothing to lose people," Morello said, inviting MC5 frontman Wayne Kramer onstage. "Right now it's time to  …!" Kramer screamed.  "Kick out the jams," the crowd screamed back, before the two sent their guitars dueling on the breakout MC5 tune. After a group singalong on Woody Guthrie's "This Land Is Your Land," Morello invited everyone up onstage for closer "World Wide Rebel Songs."