New Zealand-born Wallaby Mike Harris says he’d relish a shot at the biggest challenge in rugby – taking down All Blacks weapon Sonny Bill Williams.

Harris always dreamed of playing a Bledisloe Cup, albeit for the Blacks.

But now he’s embraced life on the opposite side of the fence and has two Australian caps to his name, the 24-year-old has turned his focus to the biggest fish in the New Zealand line-up for the Bledisloe opener in Sydney on August 18.

Harris’ laser boot won Australia the second Test against Wales in June after the full-time siren, but he wants to forge a reputation as a fearless No.12, and is happy to start by going head-to-head with Japan and NRL-bound superstar SBW.

The Queensland Reds midfielder faces a fierce battle for selection, with Pat McCabe the incumbent at inside centre and Berrick Barnes a chance to move to No.12 if Quade Cooper is reinstated at five-eighth.

But the versatile Harris could be a valuable bench option if nothing else, and said he won’t be afraid of a fired up Williams looking to make a statement in his farewell Tests.

“If I’m in that midfield role I’ll be looking to square up and make sure I come down low and don’t give him a chance,” said Harris.

“Obviously he’s a big guy and loves to get that offload away and I just think he’s got better and better with more time in the game.

“He’s definitely stamped his mark as one of the best in the world at that sort of game, throwing that offload and breaking the line – he’s definitely going to be one of the threats for the All Blacks.

“Playing in a Bledisloe Cup would just be a dream come true for me … hopefully in a few weeks that will come true. My body is feeling good and I’m raring to go and ready to get stuck in.”

Williams was expected to be excluded from the Rugby Championship after announcing he was leaving New Zealand rugby.

But new coach Steve Hansen confirmed Williams would play both matches against Australia, with the return fixture in Auckland on August 25.

Harris said Williams would be primed for a big exit, but said the Wallabies had their own motivations as they look to end a decade-long Bledisloe drought.

“If he’s made himself available for these next two games he’ll definitely be wanting to have big games before he leaves and heads off to Japan,” he said.

“It’s definitely motivation for him there but it’s exactly the same for us. We want to have two big games and put ourselves in the box seat for the Rugby Championship.”