Caddie Steve Williams didn't miss with a hefty verbal swipe at former boss Tiger Woods after new employer Adam Scott won the WGC-Bridgestone Invitational.

Now on Scott's bag after being fired by Woods, Williams used the Australian's four-shot victory against the world's best in Ohio on Sunday to vent emotion after a parting that cut deep.

"It's the greatest week of my life caddying and I sincerely mean that," said New Zealander Williams, despite having been the closest witness to 13 of Woods' 14 major titles amid 72 victories together.

"I mean, it's the most satisfying win I've ever had, there's no two ways about it. I'm not denying that."

Williams had also caddied for major winners Greg Norman and Raymond Floyd after starting his 33-year career as a 13-year-old for Peter Thomson at a New Zealand Open.

The win was undoubtedly even more satisfying for Williams because it came in Woods' comeback tournament, on the Firestone course where the American had won the event seven times.

He would appreciate the irony of earning more as a caddie with his share of Scott's $US1.4 million ($A1.34 million) winner's cheque than Woods got for finishing 18 strokes behind in a tie for 37th.

He also clearly enjoyed the shouted support from the gallery, a contrast from his days as the stony-faced, camera-grabbing custodian for Woods.

"I had no idea how popular a New Zealander can be," joked Scott. "Surprising."

Williams claimed Woods' earlier comments about being fired face-to-face were incorrect.

Woods claimed he spoke to Williams in a boardroom at the AT(&T National at Aronimik in Philadelphia in early July but Williams countered.

"That's incorrect. I was told on the phone that we needed to take a break and in caddie lingo, that means you're fired, simple as that," he said.

Williams said the phone call came after he initially asked to caddie for Scott at the US Open in June, a move Woods was unhappy with despite being out injured.

"I was absolutely shocked that I got the boot to be honest with you," Williams said.

"I've caddied for the guy for 11 years, I've been incredibly loyal to the guy and I got short shifted. Very disappointed."

Now on Scott's bag full-time the veteran of 145 tournament wins believed the Queenslander could leverage his latest victory into taking the final step to a major.

That chance could come as soon as this week's US PGA Championship.

"I wouldn't be caddying for him if I didn't think (he could win a major)," Williams said.

"These (World Golf Championships) tournaments here are very high quality tournaments. This is a very difficult golf course and it's not that different from a major championship.

"If you can win on a course like this, there's nothing to say you can't win a major."

Scott made no bones about Williams' value to his win.

"Obviously, he has such a great knowledge of this golf course and the greens," Scott said. "He's seen a guy play incredible golf, the best golf anyone has ever played around here so many times.

"He really guided me around the course nicely. When he needed to step in and just make a point of where we need to be, he did that.

"He had some great little notes in his book about putts on greens. He knows this place very well."

Scott admitted he felt the need to prove to Williams that he could compete as well as Woods when in contention.

"We all know his personality in those situations," said Scott.

"It's almost like I need to show him I've got it in me because a lot of people question it."