Diaz retires Penn at UFC 137

LAS VEGAS -- Nick Diaz punched BJ Penn straight out of mixed martial arts competition and followed it up minutes later by talking his way into a immediate fight for the welterweight championship.

Diaz won a unanimous decision against Penn by keeping the fight standing to batter him with punches for the last two rounds of the main event of UFC 137 in Las Vegas. After the fight, Penn announced that it would be his last MMA bout.

"I have a daughter and another on the way," said Penn, whose left-eye area was bloody was swelled shut. "I don't want her to see me like this."

If Penn sticks to his word, it will end one of mixed martial arts' storied careers. One of only two men to win UFC titles in two weight classes, Penn has been one of the most talented all-around fighters in MMA for a decade, going back to the early successes that earned him his "Prodigy" nickname.

Immediately following the fight, Diaz renewed his call for a showdown with 170-pound titlist Georges St. Pierre. This time, UFC President Dana White granted his wish.

They were supposed to fight for the belt at UFC 137, but UFC removed him for his failure to appear for press conferences to promote the fight. Carlos Condit, originally slated to face Penn, slid into the title bout.

St. Pierre injured his knee during training, forcing him off Saturday's card. Following his victory over Penn, Diaz used his post-fight injury to accuse St. Pierre of faking the injury, which infuriated the champion.

"Now I can have a fight with him and settle it with him, because he was very disrespectful, him and his and coach, to me," St. Pierre said Sunday. "It's been a lot. He's been saying that I've been ducking him. I've never ducked anybody. I'm not a coward."

Compustrike counted 239 punches landed for Diaz on Saturday, compared to 76 for Penn. Diaz, the former Strikeforce champion and the No. 5 welterweight in the USA TODAY/MMA Nation consensus rankings. Penn is the consensus No. 8 at 170 pounds.

The last two rounds saw Diaz especially effective, as he seemed to hit Penn at will while stalking him around the ring. But first he had to survive early danger.

As he has in past fights, Penn started strong. He took down Diaz in the first round, climbed his back and landed several right hands to the head. But Diaz, an excellent MMA grappler in his own right, avoided Penn's choke attempt, recovered to guard and regained his feet.

He found flaws in his timing and defense, particularly his willingness to absorb punches from Penn. But St. Pierre praised Diaz's victory and described Penn as a worthy opponent to defeat to earn a title shot.

Saturday was Diaz's first UFC fight in five years. He won 10 in a row fighting for EliteXC and Strikeforce during that period. He left Strikeforce as its welterweight champion earlier this year.