South Sydney have squandered a great opportunity to sneak into the NRL finals after they were thrashed 38-24 by an under-strength St George Illawarra at a packed WIN Jubilee Oval on Sunday night.

Needing to win by at least five points to leapfrog Manly into the top eight, the Rabbitohs capitulated with a lacklustre effort against a Dragons outfit that rested five of its top-line stars.

The Dragons' victory has spared Manly's season with the Sea Eagles holding onto eighth spot - despite their shock loss to the Bulldogs on Sunday afternoon - with the two sides to meet at Win Jubilee Oval next Sunday.

Dragons back-rower Ben Creagh was brilliant for the home side, bagging a first half hat-trick as the Red and Whites thrilled the 18,274 fans with exciting, attacking football to streak out to a 26-6 lead at half-time.

The club were presented with the JJ Giltinan Shield at full-time for winning the minor premiership and completed a lap of honour, and in their current form the Dragons look good things to repeat that lap on grand final day.

The Rabbitohs hopes of notching a win against the league-leaders was helped before kick-off with the Dragons opting to rest skipper Ben Hornby, Jamie Soward, Dean Young, Jeremy Smith and Trent Merrin.

But John Lang's side seemed overawed and were simply blown away in a dominant first 40 minutes by the home side.

The only concern for the Dragons ahead of the finals next weekend is with back-rower Beau Scott, who was placed on report for a late and high hit on Rabbitohs halfback Chris Sandow.

With everything to play for the Rabbitohs were expected to come out with plenty of enthusiasm and purpose but it was the home side that hit the ground running.

It took just six minutes for the Dragons to open the scoring when Creagh grabbed his first after a wonderful piece of opportunist play.

The Dragons opted to run the ball on the last tackle with Morris running down the sideline before flinging a ball back inside to Cooper just before being pushed out, with the centre spinning and passing to his back-rower backing up on the inside to score. Kyle Stanley added the extras to make it 6-0.

The Blues forward had his second just three minutes later after he outjumped Nathan Merritt to claim Nathan Fien's bomb, before getting the ball out the back to Boyd, who stepped one and returned the ball to Creagh who danced over next to the posts.

And he completed his treble inside 17 minutes when he ran into a gap close to the line off a short pass by Fien. Stanley's conversion made it 18-0 in as many minutes.

The Rabbitohs simple had no answer to the pace and execution of Wayne Bennett's side, who completed every one of their first 15 sets in the opening 25 minutes.

A high tackle by David Taylor on the Dragons' Luke Priddis saw the Souths forward placed on report and allowed the Dragons to extend the lead to 20-0 through a Stanley penalty goal.

The Rabbitohs rarely had an attacking opportunity in the Dragons' half in the opening stanza but on the occasion they did they made it count.

Chris Sandow, Luke Capewell and Taylor were all involved in a neat backline move that ended with winger Fetuli Talanoa crossing in the corner.

But it was just a hiccup for the Dragons as Brett Morris scored his 20th try of the year four minutes later to give the home side a commanding 26-6 lead at the break.

Dragons full-back Darius Boyd is in line to win the prestigious Dally M award for the NRL player of the year on Tuesday night and he did his chances no harm by grabbing the first try after half-time.

There didn't appear to be much happening when the Queensland back sauntered across field 10 metres out from the Rabbitohs line but Boyd spotted a gap and went through it and despite being halted in a tackle he managed to reach out and score.

Stanley kept up his perfect night with the boot, converting again to make it 32-6.

Despite the score the Rabbitohs continued to try and posted two quick tries through Jamie Simpson (61st) and Dylan Farrell (64th).

But the home side weren't about to let the visitors back into the match and they responded with a milestone for centre Matt Cooper, who crossed in bizarre fashion for his 100th try in the NRL.

Cooper's four-pointer came about as Fien attempted to fire a pass to Boyd but forward Jarrod Saffy got in the way with the ball comically hitting him in the head, before Cooper picked it up and beat two defenders to score.

Eddy Pettybourne scored a late try for the Rabbitohs but it was a mere consolation on a glorious night for the home side.

St George Illawarra Dragons 38
Tries: Creagh 3, Morris, Boyd, Cooper
Goals: Stanley 7

South Sydney Rabbitohs 24
Tries: Talanoa, Simpson, Pettybourne
Goals: Sandow 4