Australian Test winger Brett Morris showed his class with two first-half tries as St George Illawarra completed a hat-trick of successes for NRL teams in the annual PROBIZ World Club Challenge with a 21-15 win at Wigan Warriors.

The Dragons overcame a nightmare start to silence a near-capacity crowd of 24,268 at the DW Stadium and provide a pick-me-up for head coach Wayne Bennett, who flew back to Australia this week to be with his gravely-ill mother-in-law.

With Sam Tomkins and two-try George Carmont in superb form, Engage Super League champions Wigan looked capable of succeeding where predecessors Leeds Rhinos failed in the previous two years at the hands of Manly Sea Eagles and Melbourne Storm.

But they were undone by the devastating finishing of Morris, who demonstrated the searing pace and exceptional footwork that has brought him 11 tries in nine appearances for his country.

It was only some desperate last-ditch defence that denied him a hat-trick but his efforts were enough to earn him him the man-of-the-match award.

The Dragons showed little sign of rust on their first competitive game of the year, although they were caught cold in the opening minutes.

Wigan, who went into the game two props light with Stuart Fielden failing to recover from a knee injury and new signing Jeff Lima suspended, could hardly have made a better start.

Carmont's shuddering tackle on Dragons forward Beau Scott gifted them possession deep inside the visitors' half and, on the last tackle, the Samoan centre leapt high to reclaim Paul Deacon's high kick and score his first try with less than two minutes on the clock.

Deacon put over the conversion and made it 8-0 two minutes later after hooker Nathan Fien was penalised for a high tackle on Wigan skipper Sean O'Loughlin.

It did not take long for the Australian side to settle down, though, and they made clear their intentions to attack the Wigan right-side defence when scrum-half Ben Hornby squeezed out a pass for Matt Cooper to send his winger over for his first try on nine minutes.

That try followed a knock-on on his own 20-metre line by Warriors centre Martin Gleeson, who took his place in the side despite carrying a hamstring injury and was finally withdrawn two minutes before half-time.

Gleeson was powerless to prevent Cooper crossing for St George's second try on 16 minutes, then Morris finished decisively to claim his second on 29 minutes.

But Wigan regained the lead midway through the first half when a sloppy pass deep inside his own half from Harrison Hansen unhinged the Dragons defence, allowing Carmont to race into a gap. He showed a clean pair of heels to all pursuers on a thrilling 60-metre sprint to the line for his second try.

A Sam Tomkins drop-goal on the stroke of the interval was all that separated the sides after an enthralling first half and it was just as tight and tense in the second half.

Morris showed his danger with another devastating run while his opposite number Darrell Goulding denied him a hat-trick by getting his fingertips to a pass from Cooper - and he was also thwarted by an ankle-tap from makeshift centre Joel Tomkins.

The pressure which mounted on the Wigan line eventually told 15 minutes into the second half when replacement hooker Cameron King caught the defenders napping with a darting run from dummy-half which brought the Junior Kangaroo a try on only his second first-grade appearance.

The Dragons were forced into some desperate defence as Wigan poured towards their line in the final quarter - but Jamie Soward's 70th-minute drop goal gave them valuable breathing space