Corey Allan laid a claim to South Sydney's vacant left wing position with a hat-trick of tries in the Rabbitohs' 36-24 Charity Shield defeat of St George Illawarra - but coach Wayne Bennett played down the rookie recruit's round one chances.

Allan, who joined Souths from Brisbane this season, played fullback for the Prime Minister’s XIII and the Junior Kangaroos last season but with Greg Inglis and Alex Johnston in the Rabbitohs ranks, wing looks to be his best option.

Bennett has an opening on the wing after releasing Robert Jennings to Wests Tigers but any concerns about replacing the man who scored 19 tries in the position last season have eased after Allan’s hat-trick.

In doing so, he also exposed a selection problem for Dragons coach Paul McGregor as Allan's team-mate Zac Lomax appeared more comfortable when he was shifted from wing to centre in the second half.

However, Bennett suggested Allan was likely to be the one to make way for Inglis if the Souths captain overcame a knee problem to play in the season opener against Sydney Roosters.

"I don't see him getting a start in round one," Bennett said of Allan. "It all depends on what Greg does, but right now I don't see him getting a start.

"He's not really a winger, but that's where he played tonight. He's got a couple of good fullbacks in front of him. I don't think he'll be playing initially. Nobody doubts he's got ability, it's just a matter of maturity now."

The Dragons led 18-16 at halftime but only after overcoming a horror start in which Souths scored two tries in the opening five minutes through wingers Campbell Graham and Allan.

McGregor is trying to decide who will play right wing after the departure of Nene Macdonald to North Queensland and retirement of Jason Nightingale.

Lomax is the obvious choice but he did not convey confidence in the opening exchanges.

Rabbitohs winger Corey Allan.
Rabbitohs winger Corey Allan. ©Gregg Porteous/NRL Photos

After spilling a Cody Walker bomb near his own line, Lomax made a poor defensive read as Allan was given a clear passage to the line to score his first try in the fifth minute.

However, Lomax regained his composure to grab the Dragons' first try in the 14th minute when he dived over in the corner after receiving a cut-out pass from halfback Ben Hunt.

The new St George Illawarra spine combination of Hunt, fullback Gareth Widdop, five-eighth Corey Norman and hooker Cameron McInnes looked more fluent than it did last weekend against Newcastle.

McGregor injected fullback Matt Dufty into the game late in the second half, with Widdop moving to five-eighth, Norman to halfback, Hunt to hooker and McInnes to lock and it is a tactic he is likely to use throughout the season.

An overhead pass from Rabbitohs veteran John Sutton created Allan's second try in the 23rd minute but the Dragons gained control for the remainder of the half, with left centre Tim Lafai scoring two converted tries to put them in front just before halftime.

The signing of Norman has enabled Hunt to take on more of a running role and an inside pass from the Test and Origin representative to Korbin Sims created room for Widdop to run through a hole and put Lafai over for his first try in the 29th minute.

Dragons centre Tim Lafai.
Dragons centre Tim Lafai. ©Gregg Porteous/NRL Photos

Lafai grabbed his second three minutes later after Hunt put Tariq Sims into space and swept around behind him to create an overlap for the Samoan international and put the Dragons in front 18-16 after Widdop's conversion.

The second half began like the first, with Walker scoring from a run-around with Sutton in the 41st minute.

A Damien Cook 40/20 kick at the end of the next set put the Rabbitohs in position to post further points and lock Cameron Murray put them ahead 28-18 when he crashed over in the 44th minute.

Allan got his hat-trick in the 50th minute after Widdop fumbled a kick near his own line and his fullback opposite Alex Johnston chimed in to create an overlap for Souths after quick service from Cook at dummy-half.

Hunt put Tariq Sims over in the 57th minute but Rabbitohs rookie Bayley Sironen put the result beyond doubt when he scored 11 minutes later.