Paul Sculthorpe expects to miss the rest of the season after snapping the Achilles tendon in his left leg.
Sculthorpe only returned to action in March after six months out
The Great Britain and St Helens star was injured during training on Friday, but the full extent of the injury was not apparent until a scan on Saturday.
He has been hit by major back and knee problems over the past two years and will see a specialist on Monday.
"I can't believe my bad luck but I won't give up. I'm gutted but I will be back next season," said Sculthorpe, 29.
Sculthorpe is currently in talks with Saints, who paid a then world-record fee for a forward of £370,000 when they signed him from Warrington in 1997, over a new contract.
Speaking to the Daily Mail newspaper he added: "It is just freakish that I have picked up another bad injury.
"I had been training for about 15 minutes when I suddenly felt as if I'd been shot in the back of the leg. I've never known pain like it.
"I had three scans and was praying it was only a problem with my calf, because the first scan showed I had torn the muscle. But I had also snapped the Achilles and that means my season is over."
Sculthorpe will travel to London on Monday to see the surgeon who fixed his knee last September.
"I will see who he recommends to repair my Achilles and take it from there," he said.
"My knees are fine now and I can handle the rehab again."