The MGM Grand in Las Vegas is the place to be Saturday night for UFC fans, including Hollywood celebs who have flocked to Sin City for the July 4th weekend.

PHOTOS: Stars Come Out For UFC Event

UFC Heavyweight Champion Brock Lesnar and UFC Interim Heavyweight Champion Shane Carwin will battle it out to consolidate the most coveted belt in combat sports, and determine once and for all, who deserves the top spot in the MMA rankings.

Lesnar is a former college wrestling champ. Carwin goes into tonight's battle with a 12 - 0 record.

Holly Madison Dating UFC Star Josh Koscheck