UFC female bantamweight champion Ronda Rousey never really liked Floyd Mayweather Jr. while the boxer never really knew who she was... at first.

The rivalry of these two athletes has evolved into something deeper with Rousey recently claiming that she makes more money than the undefeated boxer "per second."

In a TMZ interview, "Rowdy" made her claim that she is actually earning more in the field of combat sports than the athlete who calls himself "The Money."

"[Floyd] said 'You make $300 million a night, then you can give me a call' ... and I actually did the math and given the numbers of my last fight, I'm actually the highest paid UFC fighter and I'm a woman. I think I actually make 2-3 times more than he does per second ... so when he learns to read and write, he can text me," Rousey challenged Mayweather.

When TMZ asked for the confirmation of this claim, Rousey said she really does earn more because "I'm just more efficient."

Meanwhile, the Los Angeles Times reported that Mayweather almost made the same call to the female UFC fighter, telling her to call him when she can already make $300 million in 36 minutes.

For his recent victory over Filipino boxer Manny Pacquiao, "The Money" was believed to have earned $138,888.89 per second while Rousey's pay check for her fight versus Bethe Correia has not been revealed.

This would certainly raise questions if Rousey could really make more money than Mayweather but she believes she does anyway.

Yahoo Sports said the two sports personalities have been linked for a long time already, since the boxer denied knowing Rousey. He even thought that the UFC champ was a man.

The female MMA fighter also took a jab on Mayweather during the ESPY awards in July.

"I wonder how Floyd feels being beat by a woman for once. I'd like to see him pretend to not know who I am now," People quoted her as saying.

She also earlier expressed they she is confident about knocking down anyone in this planet, including Mayweather.

In an earlier Reddit Ask Me Anything session, "Rowdy" was again faced with the query if she is ready to face Mayweather.

She confidently answered that she can definitely do so, if they will battle it out in a "no-rules fight."

"Floyd is one of the best boxers of all time. He would definitely beat me in a boxing match. I unfortunately don't get into 'matches.' I fight for a living. In a no-rules fight, I believe I can beat anyone on this planet," Rousey said.

"Boxing is a sweet science with strict rules that I respect very much and aspire every day to improve at. But you said ruleless fight, and that's my honest answer."