UFC on Fox 23 is a mixed martial arts event that will be held by the Ultimate Fighting Championship with a Women's Bantamweight main event card between Valentina "The Bullet" Shevchenko (58-2-1, 21 KO's) fighting out of Lima, Peru and her opponent Julianna "The Venezuelan Vixen" Peña (8-2-0, 3 KO's) fighting out of Spokane, Washington. This card is airing live tonight from the Pepsi Center in Denver, Colorado.The 3 scheduled undercard bouts are as follows:Featherweight: Alex Caceres vs. Jason KnightHeavyweight: Andrei Arlovski vs. Francis NgannouWelterweight: Donald Cerrone vs. Jorge Masvidal