The pair both failed to prove their fitness in the final captain's run on Thursday, leaving the Sharks without their key men on both edges.

Jackson Ferris will now debut in one of the vacant centre positions, with Siosifa Talakai coming in on the other.

It comes after the Sharks already lost Chad Townsend for a month with a calf strain, adding to their challenges in attack.

But coach John Morris had maintained on match eve he wouldn't take a risk with either of his centres.

"It is what it is, when you have soft tissue injuries the last thing you want to do is push them,"

"We're a bit short on numbers, you don't want to get burnt with another five or six week injury, it just compounds."

It will also put Morris on even higher alert for Friday night, giving his players one simple message: Beware the wounded Bronco.

Because as he's learned too many times before, there is no easy time for the Sharks to meet Brisbane.

Brisbane have won their last six contests with the Sharks dating back to 2017, while Cronulla has tasted success against the Broncos at Suncorp Stadium just four times.

The recent win streak includes the Baby Broncos' shock 24-22 win before Origin III last year, where Cronulla's side boasted almost 1000 more NRL games' experience than their opposition.

But this time, Morris insists his team will be ready for the attempted ambush.

"Beware the wounded Bronco," Morris warned.

"Going to Suncorp Stadium regardless of how they are going is always a really tough road trip.

"They have had the wood over us the last couple of years. We are well aware of what is coming."

Cronulla have won five of their past six, while Brisbane's troubles since the restart are well documented with just one victory in nine games.

Brisbane are also ranked last in defence this year, while the Sharks attack is the second most prolific in the NRL.

But Morris believes he saw enough in the first half of the Broncos' 46-8 loss to Melbourne last week to know his team have to be on guard.

"They had the upper hand on them. Came out and competed hard in defence," Morris said.

"They are a quality team, they haven't got the results but it isn't through a lack of effort."

Australian Associated Press