Newcastle secondrower Neville Costigan says the shell-shocked Knights are relying on the emotion of 'Old Boys Day' to pull an NRL top eight berth out of the fire against South Sydney on Friday night.

The Knights looked almost certain to make the finals a month ago when they skipped out to a four-point advantage over rivals Souths and Canterbury.

Since then they've fallen into a three-match hole and the 32-22 loss to Canterbury on Saturday night left the Knights locked on 26 competition points with the Rabbitohs and Bulldogs.

Friday shapes as a shoot-out for eighth spot between Newcastle and Souths, with the only likely exception to this being if those teams draw.

That would allow the Bulldogs to beat Canberra and sneak home in a Steven Bradbury-type finish.

Costigan said the Knights were at a loss to explain how they've let their season slip and admitted they'll need a few things to go their way on Friday night.

The support of a packed home crowd should help, as well as the annual event of Old Boys Day, where former Knights greats are honoured in front of the Novocastrian faithful.

Newcastle have an uncanny knack of winning on Old Boys Day and Costigan said they'll be relying on the extra inspiration.

"I think all those things go our way, but we've just got to get ourselves right before worrying about any other stuff," Costigan told AAP.

"The biggest thing is knowing what you've got to do first before worrying about the Old Boys and all that, but all that stuff helps us on the field and keeps us going."

Queensland hardman Costigan admitted the Knights had blown a massive opportunity by squandering a 16-point halftime advantage over the Bulldogs.

This was confirmed when Brisbane defeated Souths on Sunday, a result which, had the Knights won their match, would have virtually wiped the Rabbitohs out of the race.

Costigan said an attitude problem was to blame for the Knights' poor second-half showings against the Warriors, Brisbane and Bulldogs

"We really needed to win this game but hopefully a few things go our way and we've just got to put in for 80 minutes really," he said.

"I don't know what's happened, especially after the first half (against the Bulldogs), we were going so good and just dropped from 100 per cent to minus 100.

"We are still shell shocked about it.

"I think it's just attitude really, mental toughness."

Newcastle also have some serious injury worries.

Centre Keith Lulia (knee) is gone for the season, while secondrower Zane Tetevano (hamstring) is also in doubt for Friday night.

The club is hopeful veteran Adam MacDougall will return from a knee problem, however the status of backrower Matt Hilder is still unknown after a serious head cut suffered the week before against Brisbane.

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