The PNG Kumuls' World Cup hopes have been dealt a massive blow following the news that winger Xavier Coates was one of two outside backs returning to Australia after sustaining a hamstring injury.

A prolific tryscorer, Coates had crossed the line 16 times in just 17 appearances for Melbourne this season.

Coates was a late withdrawal from the nation's tournament opener against Tonga, picking up the injury in the captain's run. Though the team did admirably in his absence it was hoped that Coates would be able to return for the team's all-important final Group D clash against the Cook Islands.

But that wasn't to be, with scans confirming the bad news for the 21-year-old, ruling him out for the duration of the tournament. PNG officials have confirmed that Coates has left the squad, per AAP.

SYDNEY, AUSTRALIA - OCTOBER 18: Edene Gebbie of Papua New Guinea makes a break during the round 1 Rugby League World Cup 9s match between USA and Papua New Guinea at Bankwest Stadium on October 18, 2019 in Sydney, Australia. (Photo by Brett Hemmings/Getty Images)

It compounds the bad news for the Kumuls, following reports that Edene Gebbie, who also missed the Tonga clash, has been sent home with a groin injury. Gebbie had played most recently in the Kumuls' clash against the Australian Prime Minister's XIII.

Despite the fact that neither played in the opening game, the Kumuls still challenged their highly-fancied Tongan opponents, and they should still take plenty of confidence into their all-important game against the Kukis due to a backline that still contains NRL weapons Alex Johnston and Justin Olam, with a strong supporting cast.

Australian viewers can catch the all-important game on Wednesday, October 26 at 5.30am (AEDT).