Newcastle captain Andrew Johns withdrew on Sunday morning from his side's NRL encounter against the New Zealand Warriors.
Johns has a minor neck strain he sustained during a weights session last week and woke Sunday morning still experiencing discomfort.
Youngster Jarrod Mullen will replace Johns in the Knights line-up for the match at EnergyAustralia Stadium.
Club doctor Neil Halpin said early indications were that the injury is unrelated to the serious neck injury which sidelined Johns two years ago.
"It doesn't seem to be, but obviously you can't be 100 per cent sure of that," Halpin said on Saturday.
"If there is any doubt we'll get an MRI on Monday.
"But it's not the same sort of pain, he hasn't got the same sort of pain going down his arm and his hand like he did before, it's purely neck pain.
"We'll see how he pulls up."
