UFC 137: Nick Diaz sent the biggest name B.j. Penn in retirement.

Nick Diaz taking an upper hand over B.J. Penn

Nick Diaz sent the UFC�s biggest name B.J. Penn into retirement. Diaz, the Strikeforce welterweight champion, made his UFC return memorable, pummeling B.J. Penn on Saturday in the main event of UFC 137 to win a unanimous decision. Judges had it 29-28 twice and 29-27 for Diaz. Yahoo! Sports also had Diaz winning, 29-28. This UFC 137 fight card held on Oct. 29, at the Mandalay Bay Events Center in Las Vegas, Nevada.

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Penn looked good in the first round, but his cardio started fading in the second. Diaz took control in the second round, battering the tired Hawaiian with crisp combinations. Diaz took the second and third rounds easily, earning the unanimous decision in his first fight back with the UFC. After the fight BJ Penn announced his retirement. �I want to perform at the top level,� Penn said. �I�ve got a daughter and another on the way. I don�t want to go home looking like this.�

On the same night when the career of legendary heavyweight Mirko �Cro Cop� Filipovic came to an end at the hands of Roy Nelson, Cheick Kongo defeats Matt Mitrione, Roy Nelson defeats Mirko "Cro Cop" Filipovic, Scott Jorgensen defeats Jeff Curran and Hatsu Hioki defeats George Roop.

Diaz leapfrogged Carlos Condit for the next 170-pound title shot and will tentatively face St. Pierre at UFC 143 next year on Feb. 5 in Las Vegas. St. Pierre requested the fight after Diaz accused the champion of faking an injury in his post-fight octagon interview.