Hollywood star Jamie Foxx has brushed off criticism about his rendition of the US national anthem that he performed prior to the showdown between Floyd Mayweather Jr and Manny Pacquiao last Saturday.

The 47-year-old Oscar-winning actor took to the centre of the ring at the MGM Grand Garden Arena to perform before Mayweather extended his undefeated record to 48 fights with a unanimous points decision in Las Vegas.

Foxx was mocked on social media for his version of 'The Star-Spangled Banner', but during an appearance on The Ellen DeGeneres Show, the actor blamed technical issues.

"Now some people were a little upset about how it went down, but here's the thing first of all, any time a black person sings the national anthem you know we gotta - 'Oh sayyyyyyy can youuououou'," said Foxx.

"I mean that's just, ya know. But what did happen in the ring my ears came out. My inner ears. My inner ears came out and I'm singing with an organ so I can't hear what the organ is doing with the big crowd."

Video footage showed fellow Hollywood actor Jake Gyllenhaal appearing to laugh at Foxx's performance.