Manly skipper Daly Cherry-Evans warned players need to learn to adapt to the NRL's rules crackdown or more would get their marching orders after a Magic Round opening night sin bin bonanza that featured eight players.

Manly were on the right end of a contentious clash with Brisbane on Friday night which left the Broncos with six incidents on report and two players sin binned within 40 seconds of each other after referee Gerard Sutton finally tired of their head contact infringements.

The Sea Eagles had their own pair sin binned in the final minute for ruck infringements, adding to the four players marched for the same reason in the Tigers win over Newcastle earlier in the evening.

The NRL had warned clubs last week they wanted to crack down on these issues, but after referees erred on the side of caution in round nine the edict was reinforced by ARL Commission chairman Peter V'landys ahead of Magic Round and the referees quickly made players disappear.

Cherry-Evans, who is also RLPA president, warned more players would be sent for a break in the final six games of Magic Round if clubs didn't heed the warning that the NRL was finally serious about eradicating unnecessary head and neck contact from the game.

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"Obviously it seems like they're going to identify things and go down hard on it. If they stay consistent with it that's OK," Cherry-Evans said.

"But if they don't then it's only going to create more trouble for the refs which we don't want.

"They're serious about it so we need to take it seriously."

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While some may argue the excessive use of the sin bin is a knee-jerk reaction, what can't be disputed is the simple fact Brisbane had six incidents of dangerous tackles put on report.

The Broncos' lack of discipline is a sign that clubs need to be more wary of the way they play the game and not become lazy with their technique while under fatigue or give away deliberate penalties when the opposition is close to the tryline.

Previously clubs have complained that incidents were merely placed on report during games but would later attract stiff suspensions from the NRL match review committee or judiciary and there had been no benefit to their team during the game.

The perfect example of this occurred just last week when Eels pair Dylan Brown (three weeks) and Marata Niukore (two weeks) were both placed on report for incidents during the win over the Roosters but were later suspended by the NRL for their dangerous actions.

Now that the directive is to act and use the sin bin for forceful high tackles, players need to change the way they approach defence and not get clumsy or risk jeopardising the game for their team.

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"We have to be so aware of what's happening," Cherry-Evans said.

"They're cracking down and want that stuff cleaned up so we will make sure we err on the side of caution. We don't want to be down men in an important game.

"This is something they identified during the week. I don't think anyone quite realised it would be like this until tonight finished."