Kangaroos coach Mal Meninga expects clubs to try and manipulate the NRL's new captain's challenge system to stall time, even if he is a fan of the process.
The review system will have its final trial in Saturday's Charity Shield between South Sydney and St George Illawarra, before the NRL is expected to formally approve it for 2020.
An innovation of new chairman Peter V'landys, the process was initially trials in the under-20s for several years from 2012 through to 2016.
However, one issue with the system was teams deliberately using challenges to slow play, in a bid to wrestle the momentum of the game away from their opponents.
And Meninga anticipated NRL teams would attempt to do likewise.
"Rules are meant to broken or utilised to the advantage of the team," Meninga said.
"I think coaches will look at it and look at ways to help their side, under pressure at the back end of the game.
"Maybe if they are two points up to try and slow things up. It might be a good tactic."
The challenge system was trialled in a final-round match in 2016 between the Dragons and Newcastle, but not used by either captain.
On that occasion, though, teams could only challenge try-scoring plays and had 20 seconds to call for the review.
Under the new system, captains only have 10 seconds to make the call, where they can challenge anything that results in a structured restart - such as a scrum or penalty - after a stoppage.
Each team is also only given one unsuccessful challenge per game, as opposed to two under the old system.
Virtually every captain will go into the opening round blind on the process, with the Charity Shield and last week's All Stars match the only games to feature the challenge before round one.
Regardless, Meninga - who captained Canberra, Queensland Australia - said players generally knew if they had been on the bad end of a call, even in the heat of battle.
"I think you do (know). In the heat of battle and you're involved in play you have a fair idea of what's happened," Meninga said.
"You've got to be really sure if you use it at the start of or middle of a game. Most clubs you would think it would be at the end of the game."
Australian Associated Press