Ronda Rousey backs down to no one. The mixed martial arts superstar and current UFC women's bantamweight champion is currently in a verbal tussle with Boxing's pound for pound King Floyd Mayweather Jr.

Mayweather, who often boasts of his enormous wealth and earning power (he earned an estimated $300M from his May bout with Manny Pacquiao), previously said: "I've yet to see any MMA fighter, or other boxer, make over $300 million in 36 minutes, when she can do that, then call me."

This prompted Rousey to fire back at Floyd, indicating that while she may not earn as much as he does, she does have the edge in earnings-per-second. In an interview with TMZ she said: "[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."

Rousey also jabbed at the long running internet gag poking fun at Mayweather's apparent inability to read. She told TMZ that Floyd can contact her once 'he learns to read.'

Previous shots between the two included this response from a recent 'Ask Me Anything' session Rousey did on online discussion site Reddit. She told a commenter that while she respects Floyd's boxing ability, she could easily take him in a no-holds barred fight:

"Do I think I would legit beat Mayweather in a ruleless 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. 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."