Saifiti was placed on report for a crusher tackle on Gold Coast centre Young Tonumaipea in the first half of the Knights' heavy 36-6 loss to the Titans at CBUS Super Stadium.

Under new stricter penalties imposed by the NRL to try and eliminate the tackle, Saifiti's hopes of facing South Sydney at ANZ Stadium are on the line.

Even a grade one charge by the judiciary would carry a one-game ban with the early guilty plea under the crackdown.

Fight the charge and lose and Saifiti will not only miss the Rabbitohs clash, but the following weekend's semi-final if the Knights are victorious.

O'Brien says that is too steep a price to pay for a challenge he believes wasn't deliberate.

"That was always the concern bringing that in," O'Brien said of the NRL's tougher penalties for crusher tackles.

"That was a really hard one. He was coming off the line and all of a sudden they fall at your feet.

"They can't disappear. No-one's going in and training to do any of this stuff.

"It's massive to potentially miss out on a semi-final for something that he literally cannot disappear from."

The NRL has been unapologetic about the harsher sanctions despite criticism players are milking symptoms to gain penalties and have opposition players put on report.

Former Brisbane backrower and Fox Sports commentator Corey Parker spoke during Friday's match about his fear a player could miss this year's grand final for an innocuous tackle under the crackdown.

O'Brien however was remaining optimistic that Saifiti wouldn't face any further sanction for his offence.

"Hopefully he'll be okay. I think I did hear that a penalty's sufficient or something," he said.

Australian Associated Press