Hilo's BJ Penn retained his UFC lightweight world championship with a submission victory over Boston's Kenny Florian today in Philadelphia.

Penn defeated Florian in the fourth round of the main event of the UFC 101: Declaration mixed martial arts card at the Wachovia Center.

The referee stopped the bout, 3 minutes, 54 seconds, into the fourth round after Penn applied a rear-naked choke on Florian. The championship bout was scheduled for five 5-minute rounds.

"When I woke up this morning, I thought, I've been in this thing for nine years, what the hell am I doing," Penn said in the post-fight interview. "This is my dream."

Penn, who improved to 14-5-1, then made what has become a post-fight tradition: a plug for his Web site.

"I love the fans, I love Hawai'i, if you want to know anything else, go to bjpenn.com," he said.

Penn slammed Florian to the mat midway through the fourth round and then worked his way on top in the "mount" position. He then worked his way to Florian's back and applied the finishing choke hold.

Florian attempted several takedowns in the early rounds, but was never able to bring Penn to the mat.

Florian dropped to 13-4 and had a six-fight winning streak snapped.
Maui's Kendall Grove and Hilo's Shane Nelson both lost bouts by unanimous decision on the undercard.

Ricardo Almeida of New Jersey defeated Grove in a middleweight (185 pounds) bout. Grove nearly secured an armbar in the second round, but Almeida was able to escape.

Almeida, who improved to 11-3, scored several takedowns in each of the three rounds. Grove dropped to 12-6.

Aaron Riley of Washington controlled all three rounds of the lightweight (155 pounds) bout against Nelson. Riley improved 28-11-1, and avenged a loss to Nelson in March. Nelson dropped to 13-4.