Wests Tigers skipper Robbie Farah hailed his side's courageous 26-24 semi-final win over Canberra among the best in the club's history, with the underdogs defying a week of uncertainty to be one win away from an NRL grand final.

Inspired by superstar five-eighth Benji Marshall, in doubt all week with a knee injury suffered in the dying stages of the golden-point loss to the Sydney Roosters, the Tigers set up a preliminary final against St George Illawarra on Saturday week in a rematch of their famous 2005 encounter.

The Tigers went on to win the competition that season, but Farah hailed the victory over the Raiders - only sealed when young Raiders centre Jarrod Croker missed a chance from in front with four minutes remaining that would have sent the game to golden point - one of the best.

A spirited Canberra looked dead and buried when linchpin Terry Campese was stretchered off with a suspected torn ACL in his left knee 23 minutes from time.

"It goes to show how tough a group we are," Farah said.

"After last week I don't think anyone gave us a chance coming down here but we put last week behind us and that was pretty tough to do.

"To come down here and get a win away from home with so many injuries backing up after a hundred minutes, it was probably one of the best wins the club has ever had."

Having missed a number of shots in last week's epic final, Farah made a beeline for Croker after the game.

"I know what the kid was going through and that's going to hurt him a bit but I just told him to keep his head up," Farah said.

"He's a great young kid, he's had a great year and I know he'll bounce back from that so it's going to hurt him for a bit but, like I said to him, he's a quality player and he'll be back."

Marshall was brilliant with a leading hand in three of his side's four tries.

He took all of seven minutes to prove to everyone in the record 26,746-strong crowd there was nothing wrong with his legs, or his hands, sending Chris Heighington over untouched with a trademark flick pass.

It may have taken the Raiders until the 11th minute to finally get into the opposition half but the wait proved worth it, Bronson Harrison beginning his abuse of the Tigers' left side defence as he rumbled over to lock up the scores.

Marshall returned serve with a deft no-look pass for Gareth Ellis to score, the Tigers kicking out by two converted tries on 20 minutes when a scrum move allowed Lote Tuqiri to show he still had a bit enough toe to out-sprint young gun Josh Dugan on a 60 metre run to the line.

Chris Lawrence and Tuqiri need not have bothered with their tackles on Harrison as he set up Joel Monaghan to have the home side trailing 18-12 at the break.

Lawrence - back less than three weeks after breaking his jaw - scored again to give the Tigers breathing space before Campese's ultimately tragic run to set up Trevor Thurling's try got the Raiders back in the game.

An innocuous penalty allowed the Tigers to establish an eight-point lead before Canberra's Alan Tongue made up for the absence of his fellow co-captain with a burrowing try to set up a frantic finish.

"That second half spirit of the players - we got within two points to go into extra time," Canberra coach David Furner said.

"You've got to take your opportunities and we probably came up with a few errors there where we didn't put pressure on them ... I was very proud of that second half."

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