Second-rower Zeb Taia is set to miss St Helens' Challenge Cup semi-final against Halifax on July 27.
The 34-year-old is set for a minimum six-week stint on the sidelines after dislocating his shoulder in St Helens win over Leeds Rhinos on Friday.
The Super League leaders feared that the forward would need an operation after he went down under a challenge from Mikolaj Oledzki.
But Saints boss Justin Holbrook revealed that the Australian-born player won't require surgery.
"We pretty much knew straight after the game he'd dislocated his shoulder and there was a fair bit of damage there, but it is actually good news that he doesn't need an operation or anything," he said.
"It's rehab and hopefully only six weeks. It could have been worse. But it's still disappointing. He had been playing fantastic."
Meanwhile, St Helens hooker James Roby is nearing his return after undergoing surgery on his groin.
The England international will likely be fit to face Halifax on July 27, with Holbrook estimating that the 33-year-old will return in around two weeks.
"He is going really well," added Holbrook.
"He is still probably two or three weeks away but it was the right thing to do.
"We were going to try to see if we could manage him until the end of the season but he was getting more pain every day.
"Once he had his surgery he felt better straight away."
Halifax reached the last four of the Challenge Cup with a 20-16 win over Bradford Bulls on June 2.
They face Featherstone Rovers in the Betfred Championship this weekend.