B.J. Penn's latest retirement ended sooner than expected, as the former two-division UFC champion is set to coach against Frankie Edgar on The Ultimate Fighter 19 prior to making his featherweight debut against Edgar in the first quarter of 2014.

The announcement, first made on Wednesday's edition of UFC Tonight, came abruptly, but none were more surprised than UFC President Dana White.

"B.J. sends me a text that says, ‘Dana, I want to fight Ben Henderson.' So I immediately pick up my phone and call him, and he doesn't answer. This was two days ago," White explained on Thursday's FOXSports Google Hangout.

"So then B.J. calls me 45 minutes later. He's like, ‘Hey Dana, I didn't answer your phone call because I don't want you to talk me out of this. I know how you are. I know what you're going to say, and you're going to talk me out of it.' I was like, you're damn right I'm going to talk you out of it. He says, ‘The reason I want to fight Ben Henderson is because I believe if I beat Ben Henderson, you'll give me a shot to fight Frankie Edgar.' I'm like, ‘Frankie Edgar?' And he goes, ‘Yeah, I want this Frankie Edgar fight worse than anything. Those two losses are a rock in my shoe. He should've never beat me. That guy can't beat me.'"

Edgar and Penn fought twice in 2010, with Edgar stunningly dethroning the then-champion Penn via decision before outpointing him more convincingly in the rematch. Penn then shifted back to the UFC's welterweight division, where he largely struggled, ending his run with a pair of brutal losses to Nick Diaz and Rory MacDonald.

Now, with Penn having won just once in six contests since 2009, White believes the 34-year-old carries major regrets about the manner in which he ended his career, and they could be the reason Penn has decided to give it one last shot.

"B.J. is one of these guys who, I think, is fighting some demons right now, in that, if he could go back and do it all over again, I think he'd do it differently," White said.

"I'll tell you again. B.J. Penn is a legend. He's been here since the day we bought the company. Me and B.J. have had our times when we butted heads on many things. (But) if he wants it, I'm going to give it to him."