O'Donovan, who joined the Jets from Central Coast in the off-season, has faced relegation battles and promotion pushes in his career in England, Scotland and the Republic of Ireland.

The A-League is one of just two leagues worldwide not to feature promotion and relegation.

The 32-year feels promotion and relegation will happen in Australian football, but the time is not right now.

He feels the A-League should be expanded first before clubs outside the competition can challenge for promotion.

"I think in time, definitely it would be a good thing," the Irishman told FourFourTwo.

"Right now, obviously it's nowhere near being able to do that. With 10 teams and being a salary cap the difference between NPL and state league level, the gap is too big really with the teams and the foreigners the A-League clubs can sign with the salary cap, not even including marquees.

"You couldn't really do it as such at the moment but I'm sure five or six years down the line the Australian football landscape will be larger, the A-League will be bigger and there'll be more franchise teams.

"And then, there'll be opportunity for promotion and relegation without the complications of the salary cap and such. But definitely the A-League is a growing brand, I think in the next 12 to 24 months if we had a couple of more teams it's only going to help the brand.

O'Donovan chats to Jets boss Ernie Merrick at training

"Maybe five, six years down the line promotion and relegation becomes a thing because it will bring a broader spectrum of teams, the likes of South Melbourne, Marconi, Brisbane City. All these kinds of teams, I'm sure they'd be having a sniff around A-League expansion.

"I think it will happen, but I don't think it's ready for promotion and relegation just yet."

O'Donovan spent two seasons with the Mariners before heading up the F3.

The striker said Newcastle's pre-season is on track. The Jets are bidding to break a seven-year drought of missing out on the finals.

"It's going all really well," he said.

"Everyone's getting fitter and stronger and getting to know the tactics of our team with a new coach and new players. It's all moving in the right direction."