"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.
"The putt on 10, I could hardly see the green in the darkness," added Scott. "Really, I was struggling to read it, so I gave Steve the call over.
"I don't get him to read too many putts because I felt like I was reading good. I said, 'Do you think it's just more than a cup?'
"He said, 'it's at least two cups, it's going to break more than you think.
"I said, 'I'm good with that.'
"He was my eyes on that putt."
Williams, who was Tiger Woods's bag-man for 13 of his 14 major wins before an acrimonious split in 2011, leapt into the air as the ball disappeared into the cup and embraced Scott as the gallery erupted around the rainy 10th green.
There was none of the tasteless gloating from Williams that overshadowed the pair's first victory together in 2011 at the WGC Bridgestone Invitational.
Williams crowed that Scott's Bridgestone win was the 'best' of his caddying career, taking a swipe at his former boss Woods.
He later caused further controversy by making a racist remark about Woods before apologising for it.
Scott stood by Williams amid the controversy, ignoring calls to fire the New Zealander, and the caddie re-paid the favour in spades on Sunday.
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