Radiohead capped off a hot first day (Aug. 1) at the Lollapalooza music festival at Chicago's Grant Park, its set drawing heavily from its new "In Rainbows" and 1997's revered "OK Computer." A packed

Radiohead capped off a hot first day (Aug. 1) at the Lollapalooza music festival at Chicago's Grant Park, its set drawing heavily from its new "In Rainbows" and 1997's revered "OK Computer." A packed sea of 75,000 fans, which fanned out hundreds of yards from the stage, sang along to favorites like "The National Anthem," "No Surprises" and the title track from 1995's "The Bends."

Unrelated fireworks burst from behind the stage and over the Field Museum while the band banged out "Everything in Its Right Place," as fans lit up their mobile phones, further lighting the field.

The encore began with "Videotape," then with a simple click of the drum rims, the band went into the epic "Paranoid Android" from "OK Computer." Tracks like "Reckoner" and the touching "House of Cards" followed. The group was drenched in a formidable red haze for "Optimistic," then was dappled with changing lights for "2+2=5." In typical fashion, frontman Thom Yorke rarely addressed the sold-out crowd except to say thanks.

Just prior to the headliner's arrival, fellow British rock act Bloc Party whipped the crowd into a frenzy with high-energy tracks like "Banquet." On the opposite end of the field, Brendon Benson and Jack White traded off lead vocals as the Raconteurs, arresting fans with highlight "Salute Your Solution" from the recent album "Consolers of the Lonely." Earlier, the Black Keys delivered raw blues rock to crowds fresh from Cat Power's recently ended nearby set.

Elsewhere, Brazilian dance-punk act CSS played most of its recent sophomore Sub Pop album, "Donkey," while fashion almost overtook the Cool Kids' hot hip-hop set, as the duo dazzled fans with style as much as wit.

For the first time since its reinvention as a destination festival in 2005, a single day of Lollapalooza sold out at 75,000 tickets. Tickets are also gone for today but remain for Sunday.

Lollapalooza continues today with headliners Rage Against the Machine and Wilco. For full event coverage all weekend, visit Billboard's Lollapalooza microsite.