LOS ANGELES (AFP) - Verbal sparring between Floyd Mayweather and Ronda Rousey continued on Thursday as the unbeaten welterweight champ laughed off the mixed martial arts star's dig at his earning power.

"Big bank take little bank," he said in a statement that was posted on TMZ Sports.

"Let's play and see how much money you got."

Rousey, a former Olympic judoka who is the biggest star on the UFC circuit after a series of explosive victories, had taunted Mayweather on Wednesday, saying she earns more per second than he does.

His US$300 million (S$420 million) in earnings over 12 months, as calculated by Forbes in June, includes his take from his May mega-fight with Manny Pacquiao.

He said Rousey was not in his league.

However, Forbes weighed in on Thursday, saying that her calculations were correct.

After defeating Alexis Davis and Cat Zingano in a combined 30 seconds of fighting, she was, in fact, making more per second than Mayweather, even before she beat Bethe Correia in 34 seconds in her most recent fight this month.