Newcastle's bid to secure a finals berth has received a double blow after NSW Origin forward Steve Simpson and second-row partner Cory Paterson were ruled out of tonight's match against North Queensland.

Simpson, who was forced from the field in last Sunday's 38-18 loss to Canberra with concussion, also aggravated a neck injury and was advised after training yesterday that he should not play as a precautionary measure.

The 28-year-old international, who has played just 10 matches for the Knights this season, completed the session and also trained fully on Thursday. But he has been in discomfort all week after being put in a soft collar following the match in Canberra, and while scans did not show anything significant, it was decided not to risk Simpson in what is seen as a must-win match for Newcastle's top-eight hopes.

With Paterson also succumbing to a sternoclavicular injury he suffered against the Raiders, Knights coach Brian Smith has called Cameron Ciraldo and Chris Houston into what is now an 18-man squad for the EnergyAustralia Stadium clash.

Star utility Kurt Gidley was passed fit to play but will relinquish the goalkicking injuries due to a toe injury that has plagued him since last weekend. Either Wes Naiqama or Scott Dureau will replace Gidley as goalkicker.

With Jarrod Mullen and Dureau listed in the halves and skipper Danny Buderus taking care of dummy-half duties, Smith has re-issued Gidley's licence to roam.

"That's what I prefer to do, especially for myself but also the team when there's two halves calling the shots I can just float around and do what I do," Gidley told AAP.

"I think that's when we play our best when we've got the two halves named there. Last week and weeks in the past I've played a bit of fullback and then had to play in the halves when we've only had one other half or five-eighth there.

"With 'Beds' [Buderus], me and the two halves on the field at the same time, I think it's going to be good for us."

However, the Cowboys expect five-eighth Chris Bailey, who has been named on the interchange bench, to start in place of Dureau, with Mullen shifting to halfback.

Smith will finalise his line-up just before kick-off, and there is a chance off-contract forward Mark Taufua will be drafted into the side, giving him the opportunity to enhance his chances of earning a start for next season with the Cowboys. Taufua, who like prop Jesse Royal, has not been offered a new contract by the Knights, is expected to meet club officials after the match.

Having been able to retain the side from the previous weekend for the first time in four months, North Queensland coach Ian Millward is confident of an upset as his side battles to avoid the wooden spoon.

If the Knights lose they will have to beat Melbourne and Brisbane in the final two rounds to have any chance of making the finals.

Meanwhile, Parramatta centre Joel Reddy has been ruled out of tonight's match against the Bulldogs due to a hamstring injury but Feleti Mateo (knee) and Taulima Tautai (ribs) were yesterday cleared to play.

In a bonus for the Eels, Luke Burt is available to return earlier than expected from a rib cartilage injury suffered two weeks ago against Newcastle, and he will play on the wing, with Tautai moving to the centres to replace Reddy.

Playing opposite Tautai for the Bulldogs will be 18-year-old Jamal Idris - the fifth NRL debutant to be blooded by the club so far this season.

Idris's manager Sam Ayoub met the Bulldogs yesterday to continue talks about upgrading and extending the contract of the Australian schoolboys representative for the second time this year following his meteoric rise from the SG Ball competition at the start of the season.

Before then, Idris's sporting focus had been on athletics, where he was a world-ranked junior in javelin and shot put and represented Australia at last year's World Youth Championships in the Czech Republic.

The Bulldogs have also re-signed prop Fred Briggs on a one-year deal that will enable him to train full-time during the off-season in a bid to cement a regular berth in their top side.

In other news, South Sydney yesterday announced that extra security would be placed in the tunnel area of ANZ Stadium and fixed cameras installed to provide surveillance on all seating for tomorrow's clash with Canberra following last weekend's socket-throwing incident during the match against Manly.

The Rabbitohs have closed their investigation to find the rogue fan responsible for throwing a bolt at Sea Eagles centre Steve Matai as he entered the tunnel area after being sin-binned but chief executive Shane Richardson said the club had not given up on catching the perpetrator.

"Somebody out there knows who this cowardly person is, and it's only a matter of time before we know who it is as well. They will be dealt with accordingly," he said.