Retired, undefeated boxer Floyd Mayweather says a boxing match against undefeated UFC champion Khabib Nurmagomedov is "happening," although he has not offered any details.

Mayweather (50-0) retired from boxing in August 2017, immediately following a lucrative match against UFC star Conor McGregor. Mayweather's name has been linked to a comeback fight against Manny Pacquiao in recent months, however -- and now, a potential bout against Nurmagomedov.

"We're fighting," Mayweather told TMZ Sports. "I'm my own boss. I can't say what's going on on Khabib's end, but on my end we can make it happen."

When asked whether the fight would be a boxing or mixed martial arts contest, Mayweather answered directly.

"Who's the 'A-side?' He called me out so you have to come to my world," Mayweather said. "I seen in an interview, he said when he hit Conor McGregor, he knocked Conor McGregor down. He said I didn't knock Conor McGregor down. OK, Khabib. You got my leftovers. Whoop-dee-do."

Nurmagomedov (27-0) defended his lightweight championship against McGregor at UFC 229 on Oct. 6 in Las Vegas. He won the fight via fourth-round submission, and then exited the Octagon to confront McGregor's corner. The Nevada State Athletic Commission is still investigating the matter and is expected to fine and possibly suspend Nurmagomedov at a future disciplinary hearing.

The Dagestan native recently appeared alongside Mayweather's longtime adviser, Leonard Ellerbe, in a video filmed in Russia. In the video, Nurmagomedov laughs and calls out Mayweather.

"Let's go Floyd, we have to fight now; 50-0 vs. 27-0, two guys who never lose," Nurmagomedov said. "Let's go. Why not? Because in the jungle, [there's] only one king. Of course, I'm the king because he cannot drop McGregor, but I drop him easily. Let's go."

According to Mayweather, 41, a fight against Nurmagomedov would produce a higher paycheck than the one he received to box McGregor last year. Mayweather won that fight by TKO in the 10th round.

"When I face Khabib, I'm getting a nine-figure payday," Mayweather said. "Yes, more than the McGregor fight. Probably $100 million more, guaranteed. It could be somewhere upwards of $110 [million] to $200 million guaranteed."