Barnett opted for the early guilty plea on Monday after being charged with grade-three dangerous contact for the 35^th-minute incident at AAMI Park on Saturday.

The controversial tackle sparked a melee between the two teams and Barnett was criticised both on the field by Storm skipper Cameron Smith and by Foxtel commentators Braith Anasta and Brett Finch.

But in an indication that there was no intent on Barnett's behalf, he approached Hughes as players left the field at half-time to say sorry.

"It was certainly an accident," Knights coach Nathan Brown said on Monday.

"It's not something Mitch wanted to happen, but it was a nasty tackle all the same.

"Mitch has plead out there, so thankfully he's had a good record the last two years, Mitch, so he'll get three games.

"Over that time he'll get plenty of training in, but he's been playing really well.

"I thought he was one of our best players again the other day, which is pleasing, so he'll be a big loss for us."

Brown said he could understand the angry reaction to the tackle but explained that Barnett had made a split-second technical miscalculation.

"All clubs are pretty much taught the same thing, to let people's head fall through [in a tackle]," Brown said.

"He actually opened his body out to let his head fall through, and unfortunately it didn't go through, and the tackle does look nasty.

"I can acknowledge that it doesn't look good.

"But I think Barney apologised to the player at half-time, because it is a risky tackle.

"When you're messing with anything to do with the neck, it's obviously a high-risk type thing. I can understand why people are critical of the tackle."

Barnett, who has appeared in 31 consecutive games for the Knights, will miss three home fixtures against Brisbane, the Warriors and Canterbury.

Meanwhile, Brown will be hoping Newcastle's large contingent of international and Origin players return from this weekend's representative round unscathed.

Kalyn Ponga and Tim Glasby (Queensland) will do battle with NSW debutant Daniel Saifiti in Origin II in Perth on Sunday.

Herman Ese'ese, Hymel Hunt, Mason Lino and James Gavet will represent Samoa against Papua New Guinea at Leichhardt Oval on Saturday.

Mitchell Pearce (hip) and David Klemmer (wrist) would both have been picked for the Blues if fit, while Edrick Lee had to decline the chance to be a standby player for Queensland because of a quadriceps strain.

"A lot of people might see it that you've got the Origin obviously as the main event, but for some of the guys, playing for Tonga or playing for Samoa is a real highlight for them," Brown said.

"So obviously we're supportive of that."