Australia and New Zealand may be mortal sporting enemies but the two countries shared an historic Masters victory on Sunday with caddie Steve Williams showing Adam Scott the way.

"I'm a proud Australian and I hope this sits really well back at home, even in New Zealand," Scott told reporters with a laugh. "We had the kind of trans-Tasman combo out there with Steve on the bag.

With Scott trying to end decades of frustration and deliver Australia its first Masters green jacket, his 'Kiwi' caddie stepped up in the fading light at Augusta National to read the line for a 15-foot putt on the second extra hole of his playoff with Angel Cabrera.

Taking Williams's advice, Scott calmly rolled home the putt to end a pulsating battle with the two-time major-winning Argentine and spark celebrations half a world away.

Scott stood by Williams amid the controversy, ignoring calls to fire the New Zealander, and the caddie re-paid the favor in spades on Sunday.