MMA superstar Ronda Rousey has been thrown a career lifeline by one of boxing's biggest stars.

Former five division world champion Floyd Mayweather Jr. has offered a helping hand to the former UFC bantamweight champion, saying he is willing to help Rousey perfect the stand up aspect of her fighting.

Rousey suffered a heavy defeat at the hands of current bantamweight champion Amanda Nunes at last month's UFC 207 at the T-Mobile Arena in Las Vegas, going down after just 48 seconds to lose her second successive fight. It was Rousey's first bout since the November 2015 knockout loss to ex-boxing champ Holly Holm.

Most MMA experts believe Rousey's inability to properly strike, and defend herself, was her downfall against Holm and Nunes.

Mayweather and Rousey have verbally clashed previously after outspoken UFC president Dana White claimed Rousey would easily handle Mayweather if the pair were to meet in the octagon.

Mayweather is willing to leave the past in the past and assist Rousey with a comeback - if she intends to return.

"I'll work with (Rousey) if she's willing to work with me," Mayweather told TMZ Sports. "I don't have anything against anyone. I'm willing to work with anyone."

Earlier in the week Mayweather had high hopes for Rousey's future, telling FightHype that "a true champion can bounce back" and that "everything will be okay."

However, Mayweather did question Rousey's decision to take up a title fight immediately after a year-long sabbatical.

"I think that her losing had a lot to do with time off," Mayweather said. "She maybe should have competed against another female MMA fighter that wasn't as active as the female that she faced."