Attorney General George Brandis is standing up for Macklemore's appearance at the National Rugby League's final on Sunday, after former PM Tony Abbott claimed the US rapper would "politicize" the sporting event.

Macklemore is expected to perform his song "Same Love", one of his biggest hits which is about same-sex marriage.  And that has Tony Abbott turning into the preacher from Footloose, tweeting:  "Sport is sport!"

"It is one of his most popular songs and for Mr. Abbott and anyone else to say that it should be banned I think is a bizarre thing to say," Senator Brandis told the ABC's Breakfast.  "I thought Mr. Abbott believed in freedom of speech."

There's also a petition by former player Tony Wall to ban "the event (being) heavily politicised with a LGBTIQ anthem".  But Macklemore and the NRL aren't changing their plans because of the minor controversy.

"I'm going to Australia to perform at kind of the Superbowl of their rugby league," Macklemore told told 'The Cruz Show' on Los Angeles radio station Power 106.  "I'm getting a lot of tweets from angry old white dudes in Australia.  I think there's a petition today to ban me from playing it.  It's interesting times in Australia," which didn't faze him at all:  "Imma go harder."

The NRL says the performance before 85,000 fans in Sydney and a nationwide television audience will go on.

"Macklemore was chosen as the Grand Final act because he is currently one of the top acts in the world," said an NRL spokesman.  "The response from fans has been overwhelmingly positive, many young people are coming to the Grand Final just to see him.

"Naturally he will be performing his number one hits on Sunday, the fans would not expect anything less."