LAS VEGAS - Junior Dos Santos flattened Frank Mir with a huge right hand and finished him on the ground at 3:04 of the second round Saturday night, emphatically defending his heavyweight title at UFC 146 on Saturday night.

Dos Santos (15-1) picked apart the two-time ex-champion with superior boxing throughout the fight, eventually stunning Mir before finishing him with one last blow to the head. Dos Santos then wrapped himself in the Brazilian flag while celebrating his first title defense since taking the belt from Cain Velasquez last fall.

"I'm feeling awesome!" the ever-smiling Dos Santos shouted to the pro-Brazilian crowd. "It's not bad for a nice guy, huh? ... Frank Mir is a really good fighter, too. I came here to defend my belt, and I did it."

Velasquez stopped Antonio "Bigfoot" Silva late in the first round after administering a bloody beating that both thrilled and horrified fans at the MGM Grand Garden. Roy Nelson, Stipe Miocic and Stefan Struve also won on a pay-per-view card topped with five heavyweight fights, a first in UFC history.

Mir (16-6) had won three straight fights since losing a title shot to Shane Carwin in March 2010, but couldn't reclaim the belt he held in 2004 before getting into a serious motorcycle accident and again in early 2009 before losing to Brock Lesnar.

Velasquez (10-1) finished Silva at 3:36 of the first round, but only after pulverizing the 6-foot-4 Brazilian with a relentless series of blows after an early takedown. Silva (16-4) was cut on his face early in the beating, sending streams of blood down his face and onto the canvas, eventually coating both fighters' torsos.

Earlier, Nelson stopped Dave Herman with an overhand right just 51 seconds into the first round, and Miocic remained unbeaten with a second-round stoppage of fellow heralded prospect Shane Del Rosario. Struve, the 6-foot-11 Dutch heavyweight, stopped Lavar Johnson in the first pay-per-view fight.

Nelson (18-7) added another impressive stoppage victory to his list, catching Herman (21-4) with a right hand that sent him sprawling backward onto the canvas. Nelson landed one more shot before the fight was stopped, and then climbed onto the cage to rub his ample belly while his hometown crowd cheered.