Mayweather previously offered $10,000 to whoever came up with the best caption for a video of McGregor's loss to Nate Diaz
Conor McGregor has responded to Floyd Mayweather's taunts by tweeting that he is "going to break his face".
Last week, the American posted a video of Diaz's win over McGregor at UFC 196 offering fans the chance to win cash if they could think of an appropriate caption.
However, Mayweather was all talk as he failed to keep his word and give out the $10,000 for the best caption.
A video posted by Floyd Mayweather (@floydmayweather) on
McGregor went on to avenge his lone defeat in the UFC by taking a majority decision against Diaz at UFC 202 in August.
There has been speculation in recent months that McGregor and Mayweather might meet in the ring in a super-fight of epic proportions.
A boxing bout between the pair would likely come close to the 4.4 millions pay-per-view buys the Mayweather-Pacquiao fight sold in the U.S. in 2015.
McGregor recently acquired a boxing licence from the state of California, and has hinted at the possibility of a fight between the pair, but the move has been viewed as a ploy as he looks to negotiate improved contractual terms from the UFC.
However, he once again dipped his toe in the waters on Christmas Eve as he tweeted a pointed message to the boxer, saying that he was going to "break his face," and adding fuel to the fire of speculation that the two will eventually meet in the ring.
I am going to break his face pic.twitter.com/sI5jxpVGQN— Conor McGregor (@TheNotoriousMMA) December 24, 2016
Mayweather is currently retired with a professional record of 49-0 but has come out of retirement numerous times over his career. McGregor has a professional MMA record of 21-3.
The back and forth betwen the pair is likely to continue for the forseeable future but Mayweather appears to be have kept his money to himself this time but the Irishman doesn't appear to be willing to let that one lie.