Test back-rower Tyson Frizell is facing a week on the sidelines after being charged with a grade-one high tackle on Cronulla fullback William Kennedy during Newcastle's 16-14 win over the Sharks in Redcliffe on Sunday.

Knights officials were reviewing the 11th-minute incident on Monday to determine whether or not it would be worthwhile contesting the charge at the judiciary.

Given that Frizell will be banned for one game if he takes the early plea or alternatively is found guilty at the judiciary, they might feel inclined to roll the dice.

If Frizell is rubbed out, he will join NSW Origin enforcer Daniel Saifiti and strike weapon Lachlan Fitzgibbon as a frustrated spectator this weekend.

Saifiti limped off with a knee injury midway through the second half of Sunday's win and was undergoing scans and medical assessments on Monday.

The club released a statement saying he had suffered a "high-grade" medial-ligament strain that would sideline him from three to five weeks.

Fitzgibbon sat out the win against Cronulla after aggravating a shoulder injury a week earlier in Newcastle's victory against Brisbane.

He required surgery last Friday to repair cartilage damage and will not play again this season.

In their absence, O'Brien was confident the Knights had enough forward depth to continue on their quest for the finals, having climbed to outright seventh on the points table on Sunday.

"We've become accustomed to the 'next man up' attitude," O'Brien told the Newcastle Herald.

"We've had that many injuries over the last couple of years, we've learned to just get on with it. There's no point worrying about it.

"It's the nature of the beast, at the moment, and we've had enough practice to know how to deal with it."

O'Brien has a ready-made replacement for Saifiti in former Test and Origin prop David Klemmer, who has been outstanding for Newcastle in recent weeks as an interchange impact player.

"Coming off the bench, I think it's been good for both David and the team, what he's given us," O'Brien said.

"It's balanced out our team really well. But with Klemm starting up front with Jacob [Saifiti], I'm still really confident we can get a job done.

"Although that's not understating the importance of Daniel.

"The forward pack has been great all year, so I think they'll just feed off each other."

Josh King, Pasami Saulo, Jirah Momoisea and Jack Johns are the leading candidates to come into Newcastle's squad, while Brodie Jones would appear the logical choice for promotion to the starting team if Frizell is suspended.

With three regular-season games remaining, O'Brien remains hopeful Daniel Saifiti can return for the finals.

"He healed fairly well last year when he had a similar injury," O'Brien said.

"Fingers crossed."

Meanwhile, the Knights are waiting to learn if utility Connor Watson will re-sign with them or accept an offer to return to his original club, Sydney Roosters.