A measured Ricky Stuart didn't miss his team after they were thoroughly outplayed by the Newcastle Knights, losing 34-18 at Campbelltown on Sunday.

It was the Raiders' first loss of the season as they struggled from the start against a Knights outfit that was up for the fight.

Knights fullback Kalyn Ponga was excellent in his return from suspension, scoring a try and laying off three more.

There could be further fallout for the Raiders, with second-rower Joe Tapine involved in an all-in scuffle after the siren.

Stuart was left deflated by his team's performance, who will need to bounce back quickly when they face the Wests Tigers at Campbelltown - this time as the away team - on Saturday.

The Raiders' revival in the past two seasons has been built on the back of their defence, but they struggled against the Knights.

It's the first time they've conceded 30 points or more since they lost 30-24 to the Sydney Roosters in round nine last season.

"I said last week - I don't think people believed me - after beating Melbourne I wasn't happy with the way we played the second half," Stuart said.

"We played well for 40 minutes, but our second half was awful.

"Defensively tonight we were the worst we've defended for two years. It was a very, very poor showing of commitment in defence.

"And it's not just the edges. I know you're talking about the right edge. It all starts in the middle. And we played like children tonight."

Raiders five-eighth Jack Wighton had a mixed night, scoring a brilliant try to open the scoring for the Green Machine, but also producing several costly errors.

He will have to complete concussion protocols this week to be passed fit to play the Tigers after he hit his head on the ground following a head clash.

Wighton was unable to return to the field having failed his head injury assessment.

Stuart said, while there was no malice from the Knights' players, that Wighton has been targeted because of his kick chase.

It was something he told him to speak with referee Ashley Klein about before the game, but the Raiders coach won't be contacting the NRL about the issue during the week.

"Jack's been getting taken out of play after he kicks quite often," he said.

"It's something we spoke about this week. I asked him to go to the referees and talk about it onfield in regards to, 'Do I have to take this into my own hands?'

"Because he's known as a good kick chaser after he kicks he gets pulled and tugged off the ball.

"That was a late hit, but it was an accident. I don't think there was any malice in it.

"I'm pretty sure the two players involved in it wouldn't have meant to hurt Jack."

AT A GLANCE

NEWCASTLE KNIGHTS 34 (Edrick Lee 2, Bradman Best 2, Kalyn Ponga, Enari Tuala tries; Kalyn Ponga 4, Tex Hoy goals) bt CANBERRA RAIDERS 18 (Jack Wighton, Nick Cotric, Josh Papalii tries; Jarrod Croker 3 goals) at Campbelltown Stadium. Referee: Ashley Klein.