Queensland Maroons head coach Billy Slater has refused to be drawn into serious comment around Kalyn Ponga's send-off during the State of Origin opener.

Ponga was sent from the field by referee Ashley Klein with just over 20 minutes to go for what was ruled to be a shoulder charge direct to the head.

The on-field official had no hesitation in making the call, and Queensland would go on to squander what was, at the time, a 14-point lead.

Slater, though, said he had no problems with the send-off.

"It is what it is," Slater said during his post-match press conference.

"I haven't got any problems with it.

"He is okay. He feels he has let his team down. Those things happen in games, and they happen really quick. I've played that position, I know how hard it is, and in the spur of the moment, things happen, it's wet out there.

"I thought it was a courageous effort from our players. I'm heartbroken for them. The effort they put in, they played with so much heart in that last 23 minutes, and New South Wales did a great job. They had to chase the points down, and they got them, right at the death. I thought they played with plenty of spirit."

Pushed for further comment, Slater said he wouldn't make any noise.

"I haven't got a problem with it, it's fine. I'm not going to make any noise about it; it is what it is, it's a game of footy, and they have to make decisions out there. They are the breaks," Slater added.

In between Slater's two comments, Queensland captain Cameron Munster was quizzed on the view from on-field, and he claimed it was a head clash, rather than a shoulder charge.

"They were talking about the positioning, it's a spur-of-the-moment type of thing. I thought it might have been head-on-head with the split on KP's ear, but the referee and the bunker saw it differently. At the end of the day, rules are rules, and unfortunately, there was a bit of force to his head," Munster said.

"I thought it was head-on-head, but the ref has to make a split decision. We got on with it, fought our best, and unfortunately, it wasn't enough tonight."

Adding to the controversy of the matter, the NRL's match review committee only hit Ponga with a Grade 2 charge for the offence, and he will be free to play this weekend for the Newcastle Knights if coach Justin Holbrook asks him to back up.

New South Wales coach Laurie Daley, when quizzed, refused to provide an answer, only suggesting he would rather not say.