The UFC returns to Vegas on October 30 (aus time), as former two-division champion BJ Penn faces former Strikeforce welterweight champ Nick Diaz.
Georges St. Pierre was expected to defend his title against Carlos Condit on this card, but had to withdraw due to knee injury. Nick Diaz vs. B.J. Penn is now the main event.
Other big fights on the card include Cheick Kongo vs. Matt Mitrione and Mirko Filipović vs. Roy Nelson.
Watch the UFC 137 preview video: