Former two-division champion and UFC Hall of Famer B.J. Penn might not be done with his fighting career after all following an appearance on "UFC Tonight" where he all but announced his comeback to MMA.

Penn was asked about his lackluster showing against Frankie Edgar in his final fight and the issues he had with his weight cut down to 145 pounds and the work he did with noted nutritionist Mike Dolce.

That was all it took for Penn to unleash on Dolce while issuing a personal challenge to one of his current clients, who just happens to fight at featherweight, and that matchup alone would be enough to draw the Hawaiian out of retirement.

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"I'm sick and tired of hearing about Mike Dolce," Penn said. "You know what Mike Dolce, I'll put a challenge out right now -- you go grab Nik Lentz, that's your boy, bring him down to 145, I'll run right through him in one round and then I'll find you in the back and I'll smash you.

"Let's do that right now. I'm ready."

The impromptu announcement left Kenny Florian and Michael Bisping shocked so they followed up to see if Penn was serious about returning to action after retiring in 2014.

"Mike Dolce wants to say all this stuff -- I don't train, I don't do this and that -- let's do this," Penn said. "Bring (Lentz) down to 145, and I would come out for that.

"You're talking about me coming out of retirement, some things were said and got me heated. I was there, he was there to work for 20 days, I paid him $1,000 a day, and I'm not here to talk about that again but I'm just sick and tired of hearing it."

From the sound of things, Penn is contemplating a full return to MMA after a poor showing marked the end of his career.

Penn isn't training and hasn't prepared any kind of fight camp, but his loss to Edgar left a sour taste in his mouth and there are plenty of new challenges at 145 pounds that would keep the Hawaiian interested in a return to action.

At the top of the list next to Lentz is a potential matchup with current UFC interim featherweight champion Conor McGregor. When his name was mentioned, Penn's ears perked up and he immediately sounded interested in making that fight happen as well, especially considering the way he was once the biggest draw for any of the lighter weight divisions, and a fight with McGregor would surely bring in plenty of interest.

"You got him, you got Johnny-come-lately, he's out there right now and he's saying he's the lottery ticket and all of these different things," Penn said about McGregor. "When me and (Florian) fought, what did we pull in? One-point-one million (pay-per-view buys)? When I'm at my best, I think we can pull some pretty good numbers. He says he's the guy out there. I think we'd have some stuff to say."

Penn has settled into retirement with his family in Hawaii, but following his latest interview it sounds like the UFC Hall of Famer is closer than ever to pulling the trigger on a return to action at 145 pounds if he can get a matchup that interests him.

After that, Penn says there's no telling how long he might stick around.

"One-forty-five, let's do this," Penn said. "That was my last fight. It didn't go well, I had a very bad showing and I'm ready. I'm ready for something like that. I've been hanging out, I haven't stepped in the gym for two years. I would come out for the grudge match and see what happens after that. There's new fighters out there."