'You can over-think it': Wallaby admits to big World Cup concern

Aggression and discretion are strange bedfellows but it's a concept Rory Arnold and other Wallabies collision men must grapple with for the rest of the Rugby World Cup.

Australia have fronted with one of the more impressively physical packs in Japan and want that reputation enhanced when they meet a rugged Georgia in their last pool fixture in Shizuoka on Friday.

However, the tournament's strict policing of high tackles and a wave of yellow cards has left the likes of Arnold mulling how to go about his work when there's a gain line battle to win.

Towering second-rower Arnold agrees the new interpretation of high shots works against he and other tall players but has vowed to adapt his game and tackle lower.

Making a jolting, front-on tackle remains the goal but keeping it legal is the challenge for a man who stands 2.08m.

Rory Arnold knows he needs to be careful amid World Rugby's high tackle crackdown. Pic: Getty

"You can over-think it and stop playing your natural game, I guess," he said.

"I want to play aggressive and that's the way I'll play but at the end of the day, I'll be thinking about that (going low) as well, at the back of my mind.

"As locks and taller men, we just have to focus on getting those shots down because at the end of the day, the rule is no contact with the head."

The yellow cards dished out to Adam Coleman and Lukhan Salakaia-Loto last Saturday didn't prove costly against minnows Uruguay but could be result-swinging in a tight knockout match.

It's why coach Michael Cheika has made adjustments this week and will introduce undisclosed changes to Australia's defensive technique against Georgia.

Adam Coleman was sent to the bin during the Wallabies' win over Uruguay. Pic: Getty

If successful, the new approach will stay in place for next week's quarter-final against England or France.

"You've got to do something because whether it's truth or perception, we're getting the arm raised against us and we're losing players to the bin for things (high tackles) that we shouldn't be," Chieka said.

Lower tackles across the board could bring Wallaby pilferers such as David Pocock into play more than has been the case at the tournament.

A player who is quickly brought to deck could be more exposed to a turnover, something hinted at by Cheika.

"We've worked on some things for this game that will give us a better defensive line and better height in the tackle" Cheika said.

"If that means we've got to target a different area in the tackle and how we use our on-ballers, that too is also important."