St George Illawarra have lost prop Jarrod Saffy to a quad injury for Saturday night's NRL preliminary final against Wests Tigers.

Saffy failed to take part in Friday's final training session at Redfern Oval, the injury he suffered in the qualifying final win over Manly almost two weeks ago failing to respond to treatment.

John Green, who was named in an extended squad earlier in the week, will take Saffy's place on the bench alongside Nathan Fien, Matt Prior and Trent Merrin.

Utility Nick Emmett will be 18th man with rookie Kyle Stanley, prop Ricky Thorby and hooker Luke Priddis the others to miss out.

"It's a big blow for us, he's been playing well off the bench," captain Ben Hornby said of Saffy's injury.

"I'm sure whoever comes in will play well."

The Dragons have bunkered down in camp at a secret location in Sydney ahead of the preliminary final, which could be watched by a full house with over 60,000 tickets already sold.

Hornby denied there was extra pressure on the minor premiers to win the game, claiming the opportunity is there for both sides to secure a grand final berth.

"There's pressure on everyone, if you lose you're out - I don't think the pressure's any more on us than anyone else," Hornby said.

"It's do or die now so you've got to put in a good performance or you're out."

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