Newcastle coach Brian Smith is looking to Scott Dureau to step up as he waits to learn whether playmaker Jarrod Mullen will miss the rest of the NRL season through injury.

The Knights are sweating on the results of scans on Monday to determine the extent of Mullen's ankle injury suffered just five minutes into Saturday's 23-4 home win over Canberra.

Initial assessments were that he had syndesmosis ankle damage which could sidelined for anywhere between five weeks and the rest of the season.

Mullen said the injury occurred through a "freak accident" when his ankle was caught under the body of Canberra captain Alan Tongue in a tackle.

"I think I heard something, I thought I'd broken it, my whole foot went numb," Mullen said.

Smith said Mullen's replacement Dureau was now "vital" to the Knights.

Five-eighth Ben Rogers stepped up admirably in Mullen's absence and his kicking game consistently turned Canberra around as Newcastle shored up their top eight position by scoring four tries to one and turning on an heroic defensive effort.

Smith also warned the NRL could look forward to more grim struggles unless referees exerted more authority over the ruck area.

"I haven't really said anything for a long time, but if that's how we are going with the rucks and the ruck speed that we had tonight, there will be some more slugfests," said Smith.

"If you love tight tough footy, there will be plenty of it.

"At this time of the year, the ball in the wet, the dew on the ground, the rain and referees just allowing players to do whatever they like in the ruck, it was astonishing."

Following on Newcastle's equally gutsy effort last week against Melbourne, Smith was clearly delighted with the way his emerging team was developing and maturing.

"To get up physically and mentally and do it again... this time last year we would have lost that game and probably lost it by quite a way," Smith said.

The Knights have a bye this week and Smith said Saturday's win put Newcastle in a great position to make the finals.

"We are not there by any means, but the confidence we have taken out of last week's battle with Melbourne and then to back it up, that's the type of footy we are going to have to repeat," Smith said.

Smith praised Canberra and expressed wonderment at the crop of young players in the Raiders team.

Canberra coach David Furner said Saturday's loss now made it a lot harder for the Raiders to make the finals.

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