Junior Dos Santos (239) and Shane Carwin (254) both made weight well below the heavyweight limit. At 254 pounds, that's the lightest Carwin has weighed as of late coming into a fight, as he's been cutting down to 265.
Complete UFC 131 weigh-in results are after the jump.
The storyline going into Saturday's pay-per-view is that both men are calling for knockout finishes.
"You're going to get to see two of best heavyweights tomorrow and someone's going to be knocked out," Carwin told the crowd shortly after stepping off the scale. "And it's not going to be me."
When it was Dos Santos' turn to address the audience, he also promised fireworks.
"Shane Carwin is a tough opponent for me and for sure someone is going to get knocked out tomorrow night," Dos Santos said. "Don't blink."
The winner of Dos Santos-Carwin will receive a title shot against champ Cain Velasquez.
Kenny Florian, who drew a chorus of boos for wearing a Boston Bruins jersey to the stage, successfully made weight for his featherweight debut at 146 pounds. Beginning his UFC career back in 2005 as a middleweight, Florian will be fighting in his fourth different weight class come Saturday night.
Junior Dos Santos (239) vs. Shane Carwin (254)
Kenny Florian (146) vs. Diego Nunes (145)
Demian Maia (186) vs. Mark Munoz (186)
Jon Olav Einemo (261) vs. Dave Herman (233)
Vagner Rocha (155) vs. Donald Cerrone (155)
Spike TV Preliminary Bouts
Sam Stout (155) vs. Yves Edwards (155)
Jesse Bongfeldt (185) vs. Chris Weidman (186)
Krzystof Soszynksi (205) vs. Mike Massenzio (201)
Nick Ring (185) vs. James Head (186)
Dustin Poirier (146) vs. Jason Young (145)
Joey Beltran (247) vs. Aaron Rosa (261)
Darren Elkins (145) vs. Michihiro Omigawa (145)
Esther Lin, MMA Fighting" data-gallery-title="UFC 131" data-gallery-id="2913191" >
Esther Lin, MMA Fighting" data-gallery-title="UFC 131" data-gallery-id="2913192" >
Esther Lin, MMA Fighting" data-gallery-title="UFC 131" data-gallery-id="2913193" >