Daniel was replaced after suffering a shoulder injury early in the second half of Friday's 36-20 loss to the Dolphins at McDonald Jones Stadium and was unable to return.

He had his right arm in a sling after the game and Knights officials were anxiously awaiting the results of scans, amid fears he had either damaged his AC joint or suffered a dislocation.

Players who have injured their AC joint or sub-luxed (partially dislocated) their shoulder are usually able to return within a matter of weeks, after intensive physiotherapy and rehabilitation.

But depending on the severity, full dislocations can be season-ending and require reconstructive surgery.

Daniel needed a reconstruction at the end of Newcastle's 2017 campaign - ruling him out of representing Fiji the World Cup that year - and it is understood that surgery was also on his right shoulder.

Knights coach Adam O'Brien was unsure at Friday-night's post-match press conference about the extent of the damage, but admitted: "There wasn't much positive news when I walked in there from the [medical] staff, so it doesn't look great."

The Knights are already without Jacob for the next month after he was sent off in the 14-12 win against Wests Tigers eight days ago for a high tackle and subsequently suspended for five games.

In the absence of the two NSW Origin representatives, Newcastle's engine-room options are looking decidedly thin on the ground.

Off-season recruit Jack Hetherington, Leo Thompson and Mat Croker are the only remaining props with NRL experience, prompting O'Brien to suggest the club might have to ramp up their quest to sign reinforcements.

Newcastle parted company with a host of front-rowers at the end of last season, including David Klemmer (Wests Tigers), Pasami Saulo (Canberra), Jirah Momoisea (Parramatta), Sauaso Sue (Hull Kingston Rovers) and Max Bradbury (Cronulla), as well as Mitch Barnett, who the Warriors have used as a prop in their first two games.

The only middle forwards they signed with top-grade experience were Hetherington and Adam Elliott (Canberra), who is better known as a lock or second-rower than a genuine prop, but they have two vacancies left on their roster.

"It's a bit dire in the middle," O'Brien said. "Fortunately we've got a longer turnaround, so we can sit down once the dust has settled and make some plans around whether we can get someone in. We've got some spots there [on the roster]. We're going to have to do something."

The likely absence of Daniel Saifiti will add to a horrendous injury toll that already includes Elliott (groin), co-captains Kalyn Ponga and Jayden Brailey (both concussion), Tyson Frizell (ankle), Kurt Mann (shoulder), Jack Johns (ankle), Adam Clune (concussion), Simi Sasagi (shoulder) and Krystian Mapapalangi (shoulder).

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