UFC 91: Couture vs. Lesnar was a mixed martial arts event held by the Ultimate Fighting Championship (UFC) on November 15, 2008, at the MGM Grand Garden Arena in Las Vegas, Nevada. The main event featured the return of UFC Heavyweight Champion Randy Couture versus WWE's Brock Lesnar in a title bout. The decision to grant Lesnar—who was 1–1 in UFC fights at the time—the title shot was controversial at the time. Some felt it was premature and marketing driven, while others argued the relative lack of depth in the heavyweight division at the time left no clear-cut contenders to the belt.

UFC 91: Couture vs. Lesnar was a mixed martial arts event held by the Ultimate Fighting Championship (UFC) on November 15, 2008, at the MGM Grand Garden Arena in Las Vegas, Nevada. The main event featured the return of UFC Heavyweight Champion Randy Couture versus WWE's Brock Lesnar in a title bout. The decision to grant Lesnar—who was 1–1 in UFC fights at the time—the title shot was controversial at the time. Some felt it was premature and marketing driven, while others argued the relative lack of depth in the heavyweight division at the time left no clear-cut contenders to the belt.