Coverage of the 84th Ultimate Fighting Championship event held at the MGM Grand Garden Arena in Las Vegas, Nevada. Highlights include the return of Sean Sherk, who was suspended and stripped of his UFC lightweight title after he tested positive for steroids at UFC 73. Bouts featured include: B.J. Penn vs. Sean Sherk, Tito Ortiz vs. Lyoto Machida, Wanderlei Silva vs. Keith Jardine, Thiago Silva vs. Antonio Mendes, Wilson Gouveia vs. Goran Reljic and Rameau Thierry Sokoudjou vs. Kazuhiro Nakamura.