JONATHON Patton has withdrawn from Greater Western Sydney's crunch clash with Melbourne, continuing the Giants' horror run with injury.

The power forward has been ruled out with hamstring soreness and will be replaced by youngster Harry Himmelberg.

It's another test of the Giants' forward depth, with Jeremy Cameron also out with a hamstring problem and Toby Greene suspended.

The only time the Giants have been without all three forwards for a game was way back in round four, 2012.

Co-captain Callan Ward said Patton hurt himself earlier in the week at training but was still close to making the grade for the Demons game.

"He probably could play, but he only got through about 85 per cent of training (on Friday morning)," Ward said.

The 194cm Himmelberg, 21, has played six games with the Giants since last year's debut.

While Patton is a big loss for the Giants, they add almost 700 games' combined experienced through Steve Johnson, Shame Mumford and Brett Deledio.

Deledio will play his first game for the club after 243 games with Richmond.

The star midfielder has been plagued by calf injuries which have kept him sidelined in the off-season since switching to GWS.

"You don't play 240 games without hard work and he's done that ever since he walked into this football club," Ward said.

The Giants' decimated forward line ramps up the pressure on Rory Lobb to perform in his 50th game.

"He's had some games he hasn't performed at his best but, overall, he's had a pretty good year," Ward said.

"He's ready to step up for us, especially without Jon."

Third-placed GWS are looking to protect their spot in the top four, while Melbourne, sitting seventh, are desperate for a win to stay in the eight.