But in a BBC interview, Williams cast doubt on whether the 40-year-old can win another major and suggested Woods' fitness problems might have been self-inflicted.
No-one knows Woods' game better than Williams, who shared in 13 of the American's 14 major titles among 84 tournament victories together.
Their partnership broke down in 2011 and Woods has since not added to his major tally. The former world number one last played competitively in August last year.
Woods has slumped to 467 in the world rankings while he recovers from his latest back surgery and there seems no prospect of an imminent return.
Yet Williams is convinced the golfer can achieve more professional victories.
"I don't doubt he will come back to the winner's circle," Williams told 5 live Golf.
"He is a great competitor, he has an incredible work ethic - when he can work hard - and one thing he does know how to do is win.
"He has that ability to win even when he's not playing his best. But whether he comes back and wins major championships? That's going to be a very difficult task."
The four-times Masters champion looks certain to miss next month's Augusta gathering for only the second time since his debut as an amateur in 1995.
Williams was Woods' right-hand man throughout the period between 1999 and 2008 when the American dominated the game, and Williams thinks his old employer may now be regretting the way he punished his body during that spell.
"I guess when he looks back, he might question some of the activities that he did, some of the gym work that he might have done that, you know, had all these injuries escalate," he said.
Watching from a much greater distance, it seemed to me that Woods trained as an athlete rather than as a golfer. Athletes' bodies usually break down in their late 30s, certainly in terms of enabling competition at the highest level.
Is this what has happened? Does Williams see any worth to this argument?
"It is very hard to pinpoint how he has got to where he is now, but I'd have to say there is a lot merit in what you've just said," he said.
Williams was caddying for US veteran Ray Floyd in the mid-1990s when he first came across the willowy youngster who made it a career ambition to overhaul Jack Nicklaus' record of 18 major titles.
Greg Norman and Fred Couples were also in the group and they listened in disbelief while Woods contemplated carrying his drive over the fairway bunker down the right of Augusta's par-five second hole.
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"We were laughing at him just talking about it, but then he actually did it," Williams recalled in the interview which publicises the caddie's recent autobiography Out of the Rough.
Their first major triumph came at the 1999 PGA Championship when Williams gave an accurate read for a crucial putt on the 16th hole of the final round.
"That was the moment between him and me that created a real, true bond and got us going," he said.
Even though it was a vital putt, Williams had absolute confidence in his judgement. Indeed, he says the only time has ever been nervous caddying was in a bizarre and unrelated situation at the following year's US Open.
This was during Woods' epic 15-shot victory at Pebble Beach. The third round resumed early on the Sunday and Williams was unaware Woods had taken balls from his golf bag to practise his putting back at the hotel.
It meant they had to complete the closing half-dozen holes with only three balls in the bag. When one became scuffed and the oblivious Woods gave it to a young spectator, Williams started to panic.
The caddie's discomfort grew even greater when his boss drove into the ocean on the final tee, leaving just one ball left. "Put it this way, if he'd not found the fairway with the next I'd not be here talking to you now," Williams smiled.
The notion of a smiling Williams is somewhat removed from the scowling figure who often acted as much as a bouncer as a bagman in his dealings on the course. He would aggressively silence stray camera clicks and other elements that might put off his player.
"I tried to give Tiger the same playing field as everyone else," Williams said.  "Sometimes people send you over the edge, but it's just how it was at the time and I don't regret anything that I did.
"Often to the general public it wasn't acceptable," he continued. "But they didn't know the full story of what was behind the scenes and what actually happened."
The same can be said of Williams' ignorance of  Woods' multiple marital affairs that signalled the golfer's downfall in 2009. "I had no idea what was going on," he said.
These revelations ultimately put an intolerable strain on their partnership.
"The relationship was stretched to the max and it was never quite the same, we just didn't connect after that," he said.
As was well publicised at the time of his book's publication in New Zealand, Williams uses its pages to complain of, at times, being "treated like a slave" by Woods.
The caddie has acknowledged it was an poor choice of words, but within context this simile does feel a little more acceptable than when taken in isolation.
And it is impossible to imagine him resorting to such a phrase when describing his working relationship with the amiable Scott.
Williams is helping the Australian at the biggest tournaments this year and the burly New Zealander inherits one of the game's form players.
Scott won twice during the recent Florida swing, including the World Golf Championship event at Doral earlier this month. Despite these successes, Scott will bench his British caddie David Clark to harness Williams' expertise at next month's Masters.
"Caddying for Adam has been like a breath of fresh air for me," said Williams, who was at Scott's side for his 2013 Augusta triumph. "I'm really looking forward to seeing if he can win one more.
"I always say to Adam, many players win one major and that's great but to be recognised as one of the top players in the game... you want to have multiple majors beside your name."
Williams watches no golf on television and back home in New Zealand lives life following his two great sporting passions - rugby union and motorsport.
But he says he will not be off the pace when he caddies for the first time this year at the season's opening major.
"I'll get a feel straight away," he said. "It's just fantastic, I feel really privileged to be caddying for Adam and also to know I've had some part in developing his game.
"Dave Clark is doing a fantastic job out there, obviously. He's a guy like myself, one of the older caddies. He's got a young family, so he'll enjoy his time away now.
"He'll sit back while I caddie for a few tournaments and then he can come back and caddie for a few more. It's quite a good set-up."
Williams accepts we are now in a post-Tiger era but believes golf is in great health with the likes of Scott, his compatriot Jason Day, Rory McIlroy and Jordan Spieth leading the way.
You sense his enthusiasm to return to the circus and satisfy his obvious competitive edge. This quality was at the heart of the long and successful partnership with Woods.
It was not about the money, it was about the winning.
But on the subject of cash, there was one question that had to be asked: "Were you New Zealand's highest-paid sportsman for a while there?"
Williams laughed: "I couldn't answer that question because I don't know what anyone else gets paid. I did very well out of caddying for Tiger, no-one's going to deny that.
"But look at the All Blacks and our other great sportsmen and I just couldn't tell you what they earn."
These days Williams certainly trails financially in the wake of Dan Carter and co, but it would be no surprise if he banks another hefty cheque upon emerging from his semi-retirement at Augusta next month.
As Steve Williams prepares to help Adam Scott's quest for a second Masters title, the Kiwi caddie says his old boss Tiger Woods can still return to winning ways.