Sydney Roosters produced an extraordinary defensive display to beat rivals South Sydney Rabbitohs 12-4 to ensure they will face Melbourne Storm in the NRL Grand Final.

The Roosters survived a shoulder injury to Cooper Cronk, who played on but was unable to take his usual role as orchestrator of the attack or attempt kicks for goal, and claimed a hugely impressive victory.

Souths had the best attack in the league in 2018 but an engrossing contest went the way of the Roosters and the NRL's top defence as the Rabbitohs misfired with ball in hand.

Daniel Tupou, Blake Ferguson and Paul Momirovski touched down for the decisive points for the Roosters in the final game at Allianz Stadium before it is torn down and rebuilt, setting up a potential reunion between Cronk, who left the Storm for the Roosters at the end of last season, and the retiring Billy Slater.

However, the injury to Cronk and Slater's disciplinary issues - the full-back was charged with a grade-one shoulder charge on Sosaia Feki during the Storm's Preliminary Final with Cronulla Sharks and faces a hearing to decide his fate - could yet see the Grand Final be without its two biggest names.

Reynolds booted Souths into a 13th-minute lead but the Roosters responded in fine style two minutes late, James Tedesco's superb pass finding Tupou to cross in the left-hand corner.

A second Reynolds two-pointer ensured the scores were level at the break but Ferguson's outstanding finish gave the Roosters breathing room eight minutes after the restart. 

Ferguson was not anticipating Joseph Manu's offload out wide on the right but brilliantly evaded three tackles to stretch over and make it 8-4.

A series of Roosters mistakes gave Souths numerous opportunities, but a usually incisive attack could find no way through.

Despite the ailing Cronk being rendered largely ineffective, the Roosters continued to find alternative sources of inspiration and, though Siosiua Taukeiaho missed a simple penalty after a late hit on the veteran half-back, former Rabbitoh Luke Keary's kick was knocked back by Tupou and Momirovski, playing in just his third first-grade game, dotted down.

Souths had no response, the lack of composure growing the more time ticked down and when Reynolds, the hero of their dramatic win over the St. George Illawarra Dragons in the previous round, missed a penalty to bring them within a converted try, the Bunnies' race was run.

The Roosters and Storm will now meet in the Grand Final for the first time, but it remains to be seen whether Cronk and former team-mate Slater will face off on the biggest stage.