The injury sub debate has been sparked after both Australia and New Zealand lost a bowler during the first Test at Optus Stadium.
Debutant Kiwi paceman Lockie Ferguson injured his calf on the opening day and has been ruled out of bowling duties for the rest of the match.
‘CATCH OF THE SUMMER’: Steve Smith magic stuns cricket world
Australia paceman Josh Hazlewood injured his left hamstring in just his second over on Friday, with scans to determine whether he can bowl again during the Test.
With temperatures of 40 and 41 degrees forecast for the next two days, the injuries to Hazlewood and Ferguson could leave their respective teammates vulnerable to injury due to work overload.
The ICC approved the use of concussion subs earlier this year, and the rule has received widespread praise for putting the interests of player safety first.
But whether cricket should have a general injury sub is a topic that divides opinions, and Australian paceman Mitchell Starc doesn't expect an outcome any time soon.
"It took a long time to work out the whole concussion sub one, so I wouldn't have thought that (injury subs) is anywhere near around the corner," Starc said.
"It might come into things in the future. But I think that's probably another area where, like with the concussion stuff, they were worried about teams taking advantage of that.
"I think there's probably too much grey area with (injury subs) as well."
The issue of whether or not injury substitutions should be allowed in Test cricket drew mixed responses from fans.
Test cricket needs to allow one substitute per team per series eg injury sub. Now Aust and NZ a man down #AUSvsNZ— Steve Mitchell (@stevemitchell80) December 13, 2019
@7Cricket Concussion sub is for missile injury with potentially lethal consequences. A bowling tear is a fitness issue.— batemanchris (@batemanchris1) December 13, 2019
Concussion substitute rule was introduced because a head injury could result in death if a player wants to continue for the sake of their team. Muscle strains etc. have been part of the game since the year dot. If you're going to introduce injury subs then why just Test cricket?— Jeff Stewart (@JeffStew2901) December 13, 2019
In football, rugby etc if you have an injury you bring a sub on. You dont let that play carry on and weaken the team as a whole (99% of the time). Shouldnt it be the same for any retired hurt batsman, injured bowler who can only field. I know theres tradition and all that...— Ben (@BenMadd70239242) December 13, 2019
People still want the injury sub? We'll just sub in Patto no worries cheeeers pal.— cj (@cjpunt) December 13, 2019
My solution: One substitution(non concussion) allowed per series per team. Can be either for injury or tactical but only one allowed, and chosen sub by team must be selected pre game eg all arounder type logical choice. #AUSvsNZ— Steve Mitchell (@stevemitchell80) December 13, 2019
Maybe a sub isn’t a bad idea - for injuries or maybe just a tactic? #AUSvsNZ— Absolute Promotions (@absoluteprom) December 13, 2019
That’ll even it up. Part of me feels that injured players should be allowed a sub (given medical advice etc) and part of me feels injury/fitness is part of the game. Concussion subs presumably allowed as they’re nothing to do with fitness coming into the game. https://t.co/rTgn9471Wx— marc west (@westius) December 13, 2019
Hazlewood snared opener Jeet Raval with a beautiful swinging delivery in his first over.
But he grabbed at his left hamstring early in his second over before deciding he couldn't play on.
Hazlewood is now in doubt for the Boxing Day Test at the MCG, with James Pattinson or Michael Neser set to replace him.
‘It makes it tough now with a bowler down’
More immediately, Hazlewood's injury will place a bigger workload on Starc and Pat Cummins in the first Test, with NZ to resume at 5-109 on Saturday in reply to Australia's 416.
"It's never nice seeing anyone go down, especially one of your best mates," Starc said of Hazlewood's injury.
"I guess it makes it tough now with a bowler down. It certainly was for the Kiwis with Ferguson going down as well."
Australia captain Tim Paine threw the ball to former wicketkeeper Matthew Wade early in NZ's innings.
Wade only bowled two overs of his medium pacers, but he produced a few beautiful swinging and seaming deliveries in between some wayward ones.
"I might have to get some tips about how to move it off the seam like he did," Starc joked.
"He bowled a couple of gems there."