The bandwagon wheels wobbled as the Raiders hung on for life in a tense second half but their 22-12 triumph will take the lime green army to a showdown with minor premier the Melbourne Storm.

If there was a roof on Canberra Stadium, it would have been blown off with a spine-tingling post-match Viking Clap that sent Raiders fans into delirium.

After years and years of heartache and frustration, the Raiders are just one win away from a grand final berth and two wins away from their first premiership since 1994.

Canberra fans have generally woken up with Sunday hangovers in September for almost 20 years. But this time they'll rise on Sunday morning with a premiership dream well and truly alive.

They will play the Storm in their first preliminary final since 1997 and there's no doubt Canberra has turned green for Ricky Stuart's troops.

The biggest cheer was for coach Ricky Stuart as he turned to the crowd and clapped, while captain Jarrod Croker was the hero on the field.

"The boys were disappointed with last week, but to our credit they came back," Croker said.

"A massive thank you to everyone and go and get your tickets to Melbourne."

Croker showed nerves of steel as he kicked two late penalties almost on the same blade of grass that left him heartbroken six years ago when a then 20-year-old Goulburn junior missed a crucial finals kick against the Wests Tigers.

Those memories have now been erased and the courageous captain has a chance to write his own history as a Raiders leader.

The predominantly green crowd fell short of another sell out as the Raiders went on a 50-minute rampage to open up an 18-point lead.

But while there were some empty seats, the people who did turn up beat a long-standing 21-year record for the biggest turnout for two games in a row in Canberra's history.

More than 47,000 fans turned up for two games in seven days as the Dream Machine rolled on for another week.

Canberra turned green with excitement a week ago, but a two-point loss to the Cronulla Sharks sucked the air out of an over-filled bandwagon.

Fans were scrambling to get tickets for the Sharks clash but there were still 4000 up for grabs before kick-off against the Panthers.

There was a black-out in the south-western corner of Canberra Stadium as bus loads of Panthers fans infiltrated the capital and out-numbered the smattering of lime green in the hours before kick-off.

Slowly but surely the Green Machine army grew and second-rower Sia Soliola did his best to ignite the passion with some pre-game fist pumps to the faithful.

By the time the Viking clap found its rhythm, the murmuring Penrith fans holding a 'here to kill your clap sign' were completely drowned out by the roar of a city suffering from green fever.

There were still a handful of empty seats but it was still the biggest two-week turnout in Raiders history as 22,000 blocked the roads to the ground.

Blake Austin got the crowd to its feet in the 12th minute when he threw a giant dummy and fooled the Penrith defence, making two slip over and then beating another two to score the opener.

The Raiders opened up a 12-point lead before half-time when Jordan Rapana scored his 22nd try of the season, almost breaking Panthers hearts.

But Penrith scored two tries in six minutes to cut the gap to just six points with 13 minutes left and the stadium almost erupted.

That's when Croker calmly slotted a penalty to end the run and lift the Raiders into their first preliminary final in almost 20 years.

AT A GLANCE

CANBERRA RAIDERS 22 (Blake Austin, Jordan Rapana, Jarrod Croker tries; Jarrod Croker 3 conversions, 2 penalties) bt PENRITH PANTHERS 12 (Tyrone Peachey, Dallin Watene-Zelezniak tries; Nathan Cleary 2 conversions) at Canberra Stadium on Saturday night. Referees: Ben Cummins and Gerard Sutton. Crowd: 21,498.