LAS VEGAS -- With a 45-pound weight difference between them, UFC heavyweight champion Randy Couture and challenger Brock Lesnar are full speed ahead for UFC 91 Saturday at the MGM Grand Hotel & Casino.

Couture (16-8) was 220 pounds at official weigh-ins Friday, while Lesnar (2-1) tipped the scales at 265 pounds, the maximum weight allowed. Facing heftier foes is old hat for Couture, however. At UFC 68 in March 2007, Couture weighed 222.5 pounds against the 6-foot-8 Tim Sylvia’s 263 pounds. That August, Gabriel Gonzaga took the scales at 252 pounds to Couture’s 228.5 pounds.

The 45-year-old, six-time UFC champion was met with a hero’s welcome as he entered the arena and made his way to the stage in front of 2,500 attendees. UFC 91 will be Couture’s first appearance back after a contract dispute caused him to resign from the promotion in October 2007.

After an earnest staredown between himself and Lesnar, Couture called the 2000 NCAA wrestling champion one of his greatest challenges, but downplayed his whirlwind 11-year career that has included 15 title fights in 19 events.

“It’s not about the accomplishments at this point,” he told host Joe Rogan. “It’s about the competition.”

Chants of “Randy! Randy!” broke out throughout the audience.

Lesnar, on the other hand, felt the wrath of attendees inside the capacity-filled arena. The 31-year-old novice fighter was drowned out by boos as Rogan attempted to get his final words before show time.

The Minnesotan, once the youngest champion in WWE history, took the jeers in stride.

In the co-main event, lightweights Kenny Florian and Joe Stevenson both made their marks at 155 pounds. Stevenson stared down the popular ESPN MMA Live host with his usual impish grin.

Brazilian import Demian Maia got a healthy pop from the crowd as he weighed in at 185 pounds. Nate Quarry, a veteran of “The Ultimate Fighter” and a former Couture student, matched at 185 pounds. The undefeated Maia is 3-0 in the Octagon, while Quarry clocked in a victory last April against Kalib Starnes, his second fight back after undergoing spinal fusion surgery in 2006. Quarry’s standup style will square off against Maia’s Brazilian jiu-jitsu strengths.

Full UFC 91 Weigh-in Results:
Randy Couture (220) vs. Brock Lesnar (265)
Kenny Florian (156) vs. Joe Stevenson (156)
Gabriel Gonzaga (256) vs. Josh Hendricks (238)
Nate Quarry (185) vs. Demian Maia (185)
Dustin Hazelett (170) vs. Tamdan McCrory (170)
Jorge Gurgel (155) vs. Aaron Riley (156)
Jeremy Stephens (155) vs. Rafael dos Anjos (155)
Alvin Robinson (155) vs. Mark Bocek (155)
Matt Brown (171) vs. Ryan Thomas (170)