St Kilda’s in-form tall forwards pose a massive threat to Greater Western Sydney's undermanned backline this week, according to defender Heath Shaw.

Nick Riewoldt, Josh Bruce and Tim Membrey dominated against Essendon last week, combining for 11 goals and 31 marks in the Saints' emphatic 110-point demolition at Etihad Stadium.

While the St Kilda skipper is always a danger, the form of Bruce, who spent two seasons at GWS, and the addition of former Swan Membrey, has given the Saints forwardline some serious firepower in 2015.

As the only experienced player inside the GIANTS' back six, Shaw has called on his teammates to employ a manic team defence in a bid to stop the Saints' talls, and says last week's effort against Richmond showed the kind of effort that is required.

"Before the bye, I think we went away from what we did earlier in the year, so we reassessed that, came out against Richmond, and put in a really good three and a half quarter effort of really, really good defence, and that helps out the backs massively," Shaw said on Thursday.

"We need everyone to run back and defend, when you turn the ball over everyone's just got to flick the switch as quick as possible and get back on defence.

"A lot of teams across the competition are defending really, really well, you see West Coast, Sydney, Fremantle, Hawthorn, they flick the switch quicker than anyone else.

"It makes it hard for teams to get through them, we watch the best teams going around and we're trying to emulate what they do."

Bruce played 14 games at the GIANTS in their first two years in the competition, and managed just 10 in his first year with the Saints in 2014, but has been a revelation this season.

The defender-turned-forward hasn't missed a game and has kicked 37 goals.

GWS coach Leon Cameron says while it was disappointing to lose Bruce, he couldn't be happier to see the 23 year-old in such stunning form.

"We laid out a contract for him but thought he could get other opportunities elsewhere, but we're rapt with the way he's going," Cameron said.

"He's playing some great footy, we always knew he could take some really good marks, and he's got a great motor, he just had some interruptions over the pre-seasons with his shins.

"He's at the top of his game at the moment."

Cameron threw his support behind midfielder Toby Greene after the 21 year-old accepted a $1500 fine from the Match Review Panel for spitting at Richmond's Anthony Miles during the GIANTS' nine-point loss at the MCG last week.

Greene maintains he never intentionally spat at his former teammate, and Cameron says it's been a tough week for the midfielder.

"I'll back him in every day of the week. He's grown so much in the last 18 months, and he's an integral part of our footy side," Cameron said.

"We all make some little mistakes, and one thing about Toby, is that he'll own up to those mistakes."

Midfielder Stephen Coniglio (shoulder) and defender Nick Haynes (groin) got through the GIANTS' main session at Spotless Stadium and loom as likely inclusions to face the Saints.