Frankie Edgar, right, and BJ Penn exchange punches during their...

Frankie Edgar, right, and BJ Penn exchange punches during their lightweight title fight at UFC 118 in Boston. Edgar defended his title with a unanimous decision as all three judges scored it 50-45. (Aug. 28, 2010) Credit: Getty

Winning titles in two different weight classes wasn't enough for B.J. Penn. Nor was staying retired.

Penn will now drop to featherweight and coach against Frankie Edgar in the next season of "The Ultimate Fighter," the UFC announced Wednesday. That would be Season 19, and it begins filming at some point in October.

“B.J. really hates the fact that he lost to Frankie Edgar," UFC president Dana White said in a statement. It’s something that’s been burning deep inside of him for three years now."

Edgar took Penn's lightweight title at UFC 112 in Abu Dhabi in April 2010. Penn is 1-3-1 since that fight, including another loss to Edgar in the rematch at UFC 118 in August 2010 and a retirement from MMA after a loss to Nick Diaz at UFC 137 in October 2011.

Penn (16-9-2), who is one of two men in UFC history to win titles in two weight classes, emerged from retirement in December 2012 and lost by unanimous decision to Rory McDonald.

“We were trying to do Urijah Faber vs. Frankie Edgar, but Edgar didn’t want to go to 135 and Faber didn’t want to move to 145," White said on Wednesday night's edition of "UFC Tonight" on Fox Sports 1. "Then out of the blue BJ texted me and said he wants to fight Benson Henderson. I said ‘Why?’ He said: ‘I think if I beat Ben, then you’ll give me a fight vs. Frankie Edger.’ He said that’s all he wants. ‘I want to move to 145, beat Frankie, and fight for that title.’"

"When BJ gets fired up, he goes crazy and he fires me up," White added. "He wants this worse than anything and to fight at 145. It’s tough to say no to BJ. He just did a new deal with the UFC, so maybe if he wins this, then fights Ben, then fights for a title.”

After losing his title to Benson Henderson and the subsequent rematch in 2012, Edgar dropped to featherweight and challenged Jose Aldo for his title at 145 pounds. Edgar (15-4-1) lost that fight last February but returned in July at UFC 162 to beat Charles Oliveira for his first win in nearly two years.

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