Bulldogs coach Steve Folkes has slammed referee Tony Archer's decision to send off Sonny Bill Williams, saying the backrow star's high shot which put Andrew Johns in hospital did not warrant his marching orders.

While the Knights won 25-24 in a dramatic NRL season opener, the game will long be remembered for Williams' swinging left arm which left Johns lying face down on the turf unconscious in the fourth minute.

More than 18,000 supporters at EnergyAustralia Stadium held their collective breath for more than five minutes as the man widely regarded as the world's best rugby league player received medical attention.

That silence made way for chants of "off, off" from Newcastle fans as the champion halfback was being stretchered from the field, with Archer telling the Kiwi Test backrower: "Straight in the face, knocked him out, you're off."

Johns was later cleared of facial fractures, but will likely miss next Friday's clash with St George Illawarra after suffering a heavy concussion.

Williams is likely staring at a longer stint on the sideline through suspension.

But Folkes claimed his charge should never have been sent off - hinting the crowd's calls for the Bulldogs star's head had an influence on the decision.

"I think it was the wrong decision to send him off, I don't think it warranted that," said Folkes, who was also unhappy with at least one try being disallowed by the video referee.

"I've watched four-and-a-half games of football this weekend and my first impression was that I've seen that tackle 15 times already. Sometimes they've been penalised, other times they haven't been."

Asked what influence he thought the fact it was Johns playing in Newcastle had on the decision, Folkes said: "You can draw you own conclusions from that, I'm not allowed to say anything.

"They were fairly loud, it sounded like more than 18,500 people calling for his head. That could influence some people I guess."

Newcastle coach Brian Smith did not want to comment on the send off, but said of Johns: "He's a sick and sorry boy."

Johns was expected to be released from John Hunter hospital on Sunday night.

Without their chief playmaker, the Knights looked shell-shocked for much of the first half.

Despite playing a man down, the Bulldogs raced to an 18-2 lead after 18 minutes, but had a try controversially disallowed by the video referee in the 23rd to replacement forward Jarrad Hickey.

The Bulldogs took a 24-8 advantage into the break, but Newcastle scored three tries in the opening 18 minutes of the second half to level the game.

Kurt Gidley eventually broke the deadlock with his wobbly 15m field goal in the 73rd minute.

It secured Newcastle a heart-stopping win, but only after Bulldogs replacement Dallas McIlwain butchered a certain try just two minutes from fulltime when he dropped the ball cold with the line wide open.

"I don't know how may footy games I've ever coached, but I don't think on my death bed I'll ever forget this one," said Smith, who made a winning start to his tenure at Newcastle.

"I've forgot about a lot of (games) but that was one hell of a ride today."

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