Forced to deal with their own set of oppressive conditions last weekend, Newcastle will look to turn the heat up on Cronulla's makeshift back three when they meet in Monday's night's NRL clash at Toyota Stadium.

Stand-in fullback David Simmons and wingers Luke Covell and Misi Taulapapa were all nominated by Knights coach Brain Smith as potential weak links in the Sharks defensive line, the trio set to be bombarded by the probing kicking game of Newcastle No.7 Jarrod Mullen.

Simmons was thrown into the fullback role after Brett Kearney went down with a serious ankle injury in the round one win over Penrith, Taulapapa and rookie centre Blake Ferguson both struggling under the high ball when given a chance to replace Kearney last week.

"He (Simmons) probably hasn't played a lot there in the last couple of seasons and kicking-wise I think that will be an important aspect for us to try and find out how good he is at a fullback position," Smith said.

"I've got a high regard for Dave Simmons, I think he's quite a good player, but he hasn't played a lot there in the last couple of years.

"It's a tough position to play at any time, there's not a fullback in the game that doesn't make errors, but it becomes doubly difficult, maybe even more than that, if you haven't had a lot of practice at it.

"They're missing a key player in Brett Kearney and I think it will be important for us to make sure we test out that.

"It's not just the fullback, it's the combination with the fullback and the wingers that you lack when a guy hasn't been there before.

"The last plays for us and the kicking aspect of our game is going to be vital this week."

Much of the Knights preparation for the match has centred on recovery after the players were forced to endure sweltering conditions on the Gold Coast last weekend.

The disruption is nothing compared to that which the Sharks have had to endure, Kearney's injury compounded by a neck injury top Ben Ross and a club-imposed two game suspension for halfback Brett Seymour for an off-field misdemeanour.

Blake Green will move off the six man bench to replace Seymour at first receiver while Jack Afamasaga looks to have won the final interchange berth after Jacob Selmes turned out for the club's NSW Cup side on Saturday.

"Due to injury and a few other circumstances we're missing a few, but we haven't brought anyone in out of our top 25," Sharks assistant coach Shane Flanagan said.

"We've got some blokes there that we knew were going to play some first grade at some stage, it's just come a little bit early."

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