Tennis Australia boss Craig Tiley is stepping down to take up a job in the US later this year.

After months of speculation, the Australian governing body confirmed Tiley’s departure on Wednesday.

Tiley has been at Tennis Australia since starting as its player development chief in 2005. He  became the Australian Open tournament director the following year and CEO in 2013.

The South African-born ex-US college coach has presided over a period of unprecedented growth for the sport in Australia and has transformed the AO into the biggest event on the national sporting calendar.

He is Australia’s highest-paid sports administrator – last month The Age reported he took home $US1.2 million ($1.7 million) in the past year. That was slightly more than half his remuneration for the previous year.

And while Tennis Australia has at times come under fire for giving Tiley too much responsibility – once being the governing body’s CEO and boss of the AO became two different jobs – the 63-year-old insisted that notion was a fallacy.

“A couple of things that I could say unequivocally on behalf of our chair and the board, because I’ve been part of the meetings this week, is that it is going to be one role,” Tiley said.

“It actually is one role. I think that’s very much a misunderstanding.

“Those that work in the company don’t have a problem. They completely understand it. But obviously there’s a lot of people outside the company that don’t understand it completely.”

Tiley said having the CEO running the company and its biggest event was completely logical.

“The CEO is the face of the organisation and is responsible for the conversation with the externals, whether it be the members, boards or the public or the media,” he said.

“It would be like having a head coach of a team and then having someone in the back office talking to the media about how the team’s playing. It just doesn’t make any sense.”

Tiley will remain in his current role to help TA appoint his successor and support a smooth transition. He said the winning candidate would likely – but not certainly – come from within the tight-knit tennis community.

“The most important characteristics for what the board will look at for a new leader will be absolute cultural alignment,” he said.

Aside from building participation levels and ensuring TA successfully nurtured junior talent – including retired women’s world No.1 Ash Barty and top-20 men’s stars Alex de Minaur, Nick Kyrgios and Bernard Tomic – there is no question Tiley has transformed the AO into a billion-dollar behemoth in his 21-year tenure.

“It’s definitely a formula that’s worked well,” he said, while guaranteeing the Open would remain the so-called “Happy Slam” and the “Players’ Slam” long after he leaves.

“It’ll be even bigger and better,” he said.

“I’m 100 per cent confident we’ve got a plan for the next four or five years for the Australian Open, so it’s just (about) executing on that plan.

“We’ll deliver great outcomes.”

Tiley will take up his role with the United States Tennis Association later this year. He acknowledged he would leave behind a luxurious lifestyle in Melbourne to uproot his young family to alligator country in Orlando, Florida.

And all at age 63.

But with an American wife, Ali, Tiley said it was time for his tennis-loving 12-year-old twin sons and 13-year-old basketball-playing daughter to experience other joys.

“People say, ‘You’re mad’. I mean, I do have a great life here,” he said.

“I’ve got a great team. We’re achieving some awesome things and I’m incredibly proud of what’s already been achieved here.

“The big thing for me was – I do like a challenge. I like change.

“It’s also a personal decision to have the family close to their aunts and uncles, grandparents on that side, which they haven’t had the last 20 years.

“When your kids are young, it’s a good opportunity. Otherwise they miss that.”

-AAP