'Own up to it': Bennett's captain's challenge warning

South Sydney coach Wayne Bennett has told his players to own up if they make an error and not waste a captain's challenge on a frivolous appeal.

Parramatta and Canterbury both unsuccessfully used the captain's challenge in the first regular-season match played under the new rule on Thursday night, with Eels prop Reagan Campbell-Gillard later telling Channel 9: "I felt like an idiot".

Campbell-Gillard told Parramatta captain Clint Gutherson early in his side's 8-2 win that he had the ball stripped after match officials ruled a loose carry. Replays clearly showed he had lost it.

Bulldogs skipper Josh Jackson also failed to overturn a knock-on ruling against fullback Dallin Watene-Zelezniak in the second half.

Teams are only allowed one unsuccessful challenge and Bennett told the Rabbitohs players to be honest with captain Adam Reynolds if they make a mistake in Saturday night's match against Cronulla at ANZ Stadium.

"I'm not a fan of it but I am prepared to go with the game at the moment," Bennett said on Friday.

"I told my players this morning if you do something just put your hand up and own up to it. Don't tell your captain we want to challenge it because they know before anybody else."

Maintaining a challenge could be vital late in matches if the scores are close - particularly if the opposition kicks a field goal. 

Gutherson said Campbell-Gillard had been certain the ball was stripped before the incident was reviewed.

"He stood up and said straight away, 'Challenge it, challenge it. It's a strip'," Gutherson said. "I said, 'mate I'll back you'. They didn't get theirs either so all good."

Meanwhile, Bennett indicated that he was planning to carry an outside back on the bench throughout 2020 to cover the potential loss of a player due to concussion.

Alex Johnston will play from the interchange against the Sharks and Bennett, with  Bennett saying the role of wingers had become more important in the modern game.

"There's a bit more too it today, there's a lot of high balls going in the air and we got exposed against Melbourne when we lost a player early in the game and put someone on the wing. I think they scored about four tries from kicks," Bennett said.

"I think last year was a changing moment for me. We had Kyle Turner who could do a job for us and Ethan Lowe as well but I don't want to go down that path this year so much.

"HIA is really important, it can happen so quickly and most of them coming off aren’t going back on so you have got to assume you are going to lose a player on more regular occasions than in the past."