Sydney Roosters coach Trent Robinson admitted he thought Adam Reynolds should have gone to the sin-bin after hauling down Daniel Tupou in the build-up to the opening try of Thursday's 28-8 loss to South Sydney.

The Roosters opened the lead in the 11th minute when Reynolds' kick was charged down and Tupou charged forward and looked set to score before being dragged to the ground without the ball.

However, Michael Jennings pounced on the loose ball and touched down to give the Roosters the lead at Sydney's Olympic stadium - saving Reynolds from 10 minutes on the sidelines.

It proved to be a pivotal moment with Reynolds involved in the build-up to the first of Greg Inglis's three tries as the premiers slumped to a comprehensive defeat.

"I thought a professional foul was a professional foul," Robinson said.

"But I may be wrong there, Ben Cummins was clearly saying that had he (Jennings) not scored the try he (Reynolds) would have gone to the bin.

"That is probably the right rule and he knows it better than I do."

The old issue of the shoulder charge was the hot topic after the game.

During the commentary it was revealed the NRL had contacted the Nine Network asking for footage of a Sonny Bill Williams challenge that had not been picked up by the on-field officials.

Big bopper Dylan Napa was penalised during the game for a tackle where he looked to use his shoulder to bring a Souths player to the ground.

Robinson said he had no problems with the rulings if they were proven to be correct, but he feared that his two players could be singled out because of their reputations.

Sorry, this video has expired Greg Inglis scored three tries as the Rabbitohs ran over the Roosters with a dominant second-half performance. (Getty Images: Renee McKay)

Souths back rower Ben Teo was placed on report minutes after a challenge on Sonny Bill Williams - an incident that did not earn the Roosters a penalty.

"I think people were up for the clash, but we definitely forgot about the control in our areas," he said.

"I didn't get any close-ups of Napa's or Sonny's, but if they are shoulder charges, fair enough give them a penalty.

"But the refs missed one of theirs and saw the next two of ours. If they are going to get them, then get them.

"Napa's style of tackle is straight arm, separated from the body, they (referees) came about and showed us it was alright.

"If they come back and say 'yes they were shoulder charges,' then they need to get that right.

"But if they are wrong then they better be careful."

AAP