As the expanded second annual Firefly Music Festival opened its gates Saturday (June 22) for the second full day of music, noticeably refreshed fest-goers returned for a packed slate of options to sample on a sun-drenched Dover afternoon. Spared the oppressive heat that turns other such festivals into endurance marathons, Firefly continued its mission to stake its claim as the premiere East Coast musical escape from reality. Given the unfortunate tropical storm that befell Governors Ball and the double-digit-hour drive to Bonnaroo, its beginning to look more and more as though fans will walk away from Firefly 2013 singing the festival's praises. Here's the best of what happened on day two.

Stay Cool: Whether it was encouraged by fest organizers or the result of genuine concern, kudos are in order for Jim James and Kendric Lamar, who both halted their tightly run sets to grab some water bottles from back stage and toss them into the crowd.

"Share these with your neighbor," James implored, while Lamar was content with just opening the bottles and dousing his rowdy fans up front. Another fan-friendly win for Firefly.

Delaware Shakin': It's really been something to track the rise of soul-roots rockers Alabama Shakes, and they were met on the Main Stage by throngs of fans donning their signature grey shirt and belting out their ready-made-for-summer singles. The band's gospel still only consists of one album, but frontwoman Brittany Howard continues to demand attention as she coos and wails from the pulpit. 'Hold On' and 'Hang Loose' got the packed field moving as the Shakes keep on pushing forward.

More Than Zero: Aside from their two weekends at Coachella back in April, New York aughts indie faves Yeah Yeah Yeahs have been rather elusive in terms of hitting the major festival circuit. So it was a bit of a coup and a unique drawing factor when Firefly delivered Karen O and the fellas to the Main Stage for a crowd-pleasing set. New 'Mosquito' tracks like 'Slave' and show opener 'Sacrilege' (sans choir) flowed seamlessly with high-octane classics like 'Pin' and 'Date With the Night.' Ms. O bounded about the stage in her fresh red leather garb, occasionally nearly swallowing her microphone, just for good measure. Amid the flurry, the trio took time to pay tribute to the late James Gandolfini, as Karen noted and sympathized with the large number of New Jerseyans in attendance.

Well Managed: Another act absent from many festival lineups this summer is the eccentric psych-pop crafters MGMT, who brought a swirling, expansive display of light and sound to the Lawn Stage. Notorious for not feeling obligated to play their star-making hits, the band managed to find a happy balance between material from 'Congratulations' and their forthcoming album, as well as party starters and lighter igniters like 'Time to Pretend and 'Electric Feel.' With the legendary Tom Petty waiting in the wings a field over, a large percentage of fest goers never felt compelled to exit to get a good spot and were rewarded with an exciting, experimental, expert set from a band approaching or already in their prime.

As day turned into night, many shimmied and shook along with Tom Petty & the Heartbreakers, while others chose to sit back and enjoy the starry sky. Firefly looks poised to complete the three-day sweep today.

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