Guarda su Altadefinizione. UFC 61: Bitter Rivals was a mixed martial arts event held by the Ultimate Fighting Championship on Saturday, July 8, 2006. The main event was a Heavyweight Championship match between champion Tim Sylvia and former champion Andrei Arlovski. The co-main event was the highly anticipated re-match of TUF 3 coaches Tito Ortiz and Ken Shamrock.