Former St Helens star Mose Masoe is likely to miss the duration of 2016 after tearing his ACL.
Masoe, who signed for NRL side St George Illawarra Giants ahead of the new season, suffered the injury on Wednesday.
“Unfortunately, we can confirm that Mose has suffered an ACL injury at training during training on Wednesday that will require surgery and a six-month rehabilitation period,” said Dragons head of medical & performance Tony Ayoub.
“He will undergo surgery in the next week and commence his rehabilitation program following that.
“It is devastating for Mose as well as all the players and staff here at the club.
“He has worked so hard since returning from England and had shed the kilograms to be as fit as he has ever been in order to be ready to make a real impact for the Dragons in the NRL this year.
“Mose was simply taking a hit-up and stepped off his right leg at the defensive line and felt his knee give way.
“There was no contact from anyone else, it was a simple action that he and others perform every day with a seriously unfortunate outcome.
“As can be expected, he is very disappointed but is extremely positive about his rehabilitation.”
