Nick Diaz, B.J. Penn make weight

LAS VEGAS -- Nick Diaz and B.J. Penn have expressed a lot of respect for one another in the buildup to UFC 137, but that didn't stop president Dana White from quickly separating the two during Friday's official weigh-in.

The main-event fighters came together somewhat awkwardly during the typical Friday staredown, prompting White to step in immediately. More importantly, both came in on weight -- Diaz (26-7) right on at 170 pounds; Penn (16-7-2) at 169.

"He's a good opponent. It's time to fight," Penn said.

Featherweight Tyson Griffin (15-5) was the only athlete featured on the 11-fight card to miss weight. Griffin tipped the scale at 149 pounds -- three pounds over the allowed limit. He was given one hour by the Nevada Athletic Commission to lose the weight.

Griffin has fought the majority of his career as a lightweight. Following a three-fight losing streak at 155, he dropped to featherweight earlier this year and scored a decision win over Manny Gamburyan.

Roy Nelson (15-6) weighed in at 252 pounds for his heavyweight fight against Mirko Filipovic (27-9-2). Nelson, who typically has weighed in at the 265-pound limit would have came in even less had he not been wearing a fat suit underneath his clothes.

Filipovic, who admitted Thursday this weekend could mark his last fight, weighed in at 235 pounds.

Light heavyweight Brandon Vera (11-5) weighed in at 205 pounds for his first appearance since a unanimous-decision loss to Thiago Silva (14-2) threatened to end his tenure with the UFC. Japanese featherweight Hatsu Hioki (24-4-2) came in at 145 for his UFC debut against George Roop (12-7-1).

Brett Okamoto covers mixed martial arts for ESPN.com. Follow him on Twitter.