Newcastle's bright start to the NRL season has quickly been grounded, with crafty hooker Isaac De Gois undergoing surgery for a broken thumb.

As the worst fears for star recruit Neville Costigan were also confirmed, De Gois went under the knife on Monday afternoon and could miss a month of football.

The Knights shot to an early season first place on the ladder with Sunday's resounding 42-8 win over Penrith but now head to Townsville to play North Queensland without De Gois, Costigan and possibly captain Kurt Gidley.

Coach Rick Stone had been hopeful De Gois had jarred the thumb at Centrebet Stadium.

"He's got a fracture at the base of his thumb which is going to keep him out for three to four weeks," Stone told AAP.

Costigan, a premiership winner with St George Illawarra last year, will miss 3-4 months.

"He's really disappointed, Nev, he had a big pre-season, first game for the club," Stone said.

"He leads a lot with his actions and he had brought a bit of that toughness to us."

The club says Gidley is some chance of overcoming back spasms in time for Saturday's match.

"We haven't got the report back but our doctor Neil Halpin has had a look at the scans and basically he's all but ruled out any major injury," Stone said.

"Kurt's still a bit stiff and sore at the moment and ... it all depends on how his back and body loosens up over the next couple of days.

"He's had a similar injury around Origin last year and still got away with playing inside a week so probably at least it's something he's a little bit understanding of."

Elsewhere, Manly face a major test of their depth with co-captain Jamie Lyon sidelined for 2-4 weeks with a hamstring injury.

It leaves the Sea Eagles' centre stocks seriously depleted, with New Zealand international Steve Matai suspended until round five.

Compounding the bad news for Manly, Lyon's co-captain Jason King faces a week on the sidelines after he was handed a grade one dangerous contact charge for leading with his knee during Saturday night's loss to Melbourne.

And Sea Eagles backrower Shane Rodney will miss six weeks with a shoulder injury after making a return from a knee problem in the NSW Cup.

In some good news for Manly, winger William Hopoate's shoulder injury is not as bad as first thought and he could be available for Sunday's clash with the Sydney Roosters.

Canberra captain Alan Tongue will see a specialist on Tuesday but will miss 4-6 weeks with an injured AC joint.

The inspirational skipper also missed a large chunk of the 2010 season, managing just 12 games.

Fullback Josh Dugan (calf) and halfback Matt Orford (groin) both ran on Monday but coach David Furner isn't counting on their availability with a short turnaround to Friday night's clash with Brisbane.

"It's a matter of seeing how they pull up tomorrow," Furner said.

"Being a short turnaround, we've only got one training session. So the decision will be made fairly quickly."

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