Cameron Smith's defection to the Saudi-funded LIV Golf circuit is the biggest blow yet to the US PGA and European Tours in a power struggle threatening to rip the sport apart.

Before the capture of the 29-year-old world number two on Tuesday, LIV Golf had been derided as a place for players past their prime to swell their pension funds.

No longer. Australia's Smith is enjoying the best year of his career and is one of the biggest draws in golf after winning the 150th Open Championship at St Andrews in July for his first major.

The colourful Smith, who sports a mullet and moustache, will make his LIV debut in Boston on Friday after reportedly banking more than $100 million to leap across the widening rift between the old and new forces in the sport.

The new circuit has been accused of "sportswashing" Saudi Arabia's human rights record, backed by the almost unlimited resources of the kingdom's sovereign wealth Public Investment Fund.

Saudi Arabia has drawn major criticism over the murder and dismembering of journalist Jamal Khashoggi in its Istanbul consulate, and for cracking down on rights activists, many of whom have been jailed.

Smith, who will now be kicked off the International team for September's Presidents Cup, admitted to Australian Golf Digest that money was a motivator.

"It was obviously a business decision for one and an offer I couldn't ignore," he said.

Four-time major winner Rory McIlroy has been one of LIV's fiercest critics and reportedly spoke to Smith to make sure that the Australian knew exactly what he was getting in to.

"Any decision you make in your life purely for money usually doesn't end up going the right way," McIlroy said earlier this year.

"I just don't see the value in tarnishing a reputation for extra millions."

The brainchild of Australian former world number one Greg Norman, the LIV Golf Invitational Series is gathering momentum after a stuttering start that only drew more attention to where the money was coming from.

Norman drew scorn after dismissing the 2018 murder of Khashoggi as a "mistake". Amnesty International called the remarks "seriously misguided".

It is not only golf. Saudi Arabia has piled huge sums into hosting Formula One, world heavyweight championship boxing and buying Premier League Newcastle United, as it bids to use sport to improve the country's image.

Norman knows that he has now pulled off a major coup in snaring Smith along with the likes of 19th-ranked upcoming talent Joaquin Niemann.

"The best and the brightest continue to embrace the excitement and energy of LIV Golf and what we're building," Norman declared.

Until now, multiple major winners Dustin Johnson, Phil Mickelson, Bryson DeChambeau and Brooks Koepka had been the most notable LIV signings, but all are battling poor form or fitness, or advancing years.

Other well-known LIV recruits such as Lee Westwood, Ian Poulter and Sergio Garcia are past their best, but Smith is credible, with a game that can help LIV counter jibes that it is just an exhibition circuit.

The US PGA Tour has been quick to ban players who jump ship. But it has been slow to counter LIV's megabucks and innovative 54-hole shotgun start format, where a day's play is condensed into a TV-friendly four-hour window.

After an elite players-only meeting last week hosted by Tiger Woods and McIlroy, the tour announced new events featuring all its top players for $20 million purses, bigger than any of this year's majors.

It wasn't enough to sway Smith or any of the five other new LIV recruits announced this week, also including India's number one Anirban Lahiri and another Australian, Marc Leishman.

There could be more to come after the Presidents Cup, with the 2021 Masters winner Hideki Matsuyama and Japan's massive golf market a prime target.

Matsuyama, a hero back home, was intriguingly not on a list of headline players for the PGA Tour's Zozo Championship in Japan next month, where he is defending champion.

The LIV circuit makes its Asian debut in Bangkok earlier in October and it would be a bitter blow to the PGA Tour if their biggest Asian star instead turns up there.

The Asian Tour has already teamed up with LIV, receiving a $400 million windfall in Saudi cash.

Lahiri believes attitudes to LIV will change and it can do for golf what the Indian Premier League did for cricket -- and it won't just be the players who are the winners, he says.

"I remember the almost vehement opposition the IPL received," said Lahiri.

"Look at it now. The Board of Control for Cricket in India is laughing all the way to the bank and so are the players."

"The broadcasters are (also) delighted because they get off-the-chart ratings," he added.