UFC on Fox 21 is a mixed martial arts Welterweight main event card produced by the Ultimate Fighting Championship (UFC) between Demian Maia (23-6-0, 3 KO's) from São Paulo, Brazil and his opponent Carlos "The Natural Born Killer" Condit (30-9-0, 15 KO's) from Albuquerque, New Mexico. This card is being broadcast live tonight from Rogers Arena in Vancouver, British Columbia, Canada.

The scheduled undercard bouts are as follows:

Featherweight: Anthony Pettis vs. Charles Oliveira

Lightweight: Joe Lauzon vs. Jim Miller

Women's Strawweight: Paige VanZant vs. Bec Rawlings