Benji Madden was a knock out on Saturday night in Las Vegas.

The Good Charlotte guitarist fought former MTV host Riki Rachtman in a celebrity boxing match and knocked him down three times before the referee deemed him the winner.

Benji's twin bro Joel and their other brother Josh came out to Ellis Mania at The Joint, by Rogue at Hard Rock Hotel & Casino, in support of their sibling. Former "Girl Next Door" Holly Madison and her gal pals wore "Team Benji" t-shirts and also cheered the rocker on to victory.

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