Newcastle forward Jack Hetherington has been handed a one-game suspension after a tunnel altercation with Canterbury hooker Reed Mahoney.

Hetherington and Mahoney were sent to the sin bin in the dying moments of the Bulldogs' heated 36-12 NRL win on Sunday.

But tensions carried into the tunnel, with Hetherington waiting for the Bulldogs No.9 while bouncing on his feet like a boxer shaping to throw a punch.

Hetherington then appeared to push Mahoney in the chest before the duo were pulled apart by NRL officials.

The Knights prop was handed a grade-two contrary conduct charge on Monday which was accepted without contest and rules him out for a week.

Mahoney can escape with a $1000 fine after being handed a grade-one charge for the same offence.

Hetherington's suspension could not come at a worse time for the Knights, who have won just two games to start the season, are languishing in 15th spot and face the high-flying Dolphins on Sunday.

Adam O'Brien's men will be without captain Kalyn Ponga for the foreseeable future due to a foot injury as they struggle to recapture the form that spurred them to last year's finals series.

"We're playing like a frustrated team," O'Brien said on Sunday.

"We're not enjoying it at the moment because the expectation is that we played well last year.

"We've got to get back to find our love of the game."