Sydney Swans cult figure Lewis Roberts-Thomson is happy Greater Western Sydney are slowly growing into the beast the AFL wants them to be.

It's hardly the party line before a derby clash.

But as a local who went to one of many rugby-mad private schools on Sydney's north shore, Roberts-Thomson recognises the immense upside of another team in town.

The Giants might not be living up to their moniker for now, but plenty throughout the league hold great expectations of long-term success.

On the field, GWS capped a meritorious pre-season when they finished over the top of St Kilda in a 16-point win.

Off the field, the Giants have 11,119 members - already more than the club tallied in its maiden season.

"I think the fact they're becoming more recognised in Sydney is a good thing," Roberts-Thomson told AAP ahead of Saturday's cross-city clash at ANZ Stadium.

"No doubt their membership has grown and the club has really started to take a bit of a foothold in the Sydney market here.

"It's great for the game of AFL ... everyone (in the league) wants to promote the game of AFL.

"If we can get a match (in Sydney) every week, it goes a long way to really bringing the game up to speed with some of the other codes."

Jonathon Patton, one of three No.1 draft picks on the Giants' books, believed the Swans had a lot to do with the increased interest.

"I think Sydney's warming to the Giants a little bit more. Especially after the Swans won the premiership last year, it's created a bit more of a buzz," Patton said.

GWS aren't expected to challenge the Swans for a few more years, but made a case for that timeframe to be reconsidered in a 24-point pre-season win.

The reigning premiers fielded an inexperienced side in that February 24 clash, but were nonetheless beaten by a team that's tipped to collect their second wooden spoon in as many years.

"We saw in round one of the NAB Cup just how good they can be," Roberts-Thomson said.

"They've had a solid pre-season and they must be going into the season with confidence.

"I think the Giants have had some tremendous improvement across the board. They've recruited some bigger bodies and wonderful youngsters."