Sharks and Papua New Guinea hooker James Segeyaro.

With coach Shane Flanagan's criticism ringing in their ears, Sharks hooker James Segeyaro is adamant Cronulla's pack needs to be better if the side is to regain momentum heading into the finals.

Cronulla's defence hasn't been up to scratch during the last couple of weeks, with a narrow loss to Brisbane followed by 33 points conceded in a shock defeat against Manly last weekend.

Flanagan described the team's defensive effort against the Sea Eagles as unacceptable and with a trip to Melbourne to face the premiers this weekend, Segeyaro said the forwards had to lift.

"I've reviewed the game a couple of times now and I think Manly ran harder than us - their forward pack was a little bit more aggressive than ours," Segeyaro said.

"I think we're definitely going to suit up for a physical game (against the Storm) and it's on us in the middle to set the platform.

"They have big boys like Jesse Bromwich, Nelson Asofa-Solomona and obviously the world's best No.9 (Cameron Smith) who controls the game, so it's on us to get over their forward pack and really set the momentum for the backs."

Cronulla are sixth on the Telstra Premiership ladder, but their last two performance haven't lived up to their own lofty expectations.

Sunday could be the last time the Sharks face Billy Slater, with the all-time great announcing on Wednesday he'll be retiring at the end of the 2018 season.

"It's going to mean a lot to them (the Storm), but it's going to have to mean more for us," Segeyaro said of the game.

"Our season is on the line for a top-four spot - the last couple of weeks we've mentioned that so this is pretty much do-or-die for us."

Segeyaro said Slater has been a great role model for the game, but any admiration will be put on hold for 80 minutes at AAMI Park.

"He's a competitor," Segeyaro said.

"Every time we have attacked their line he's just everywhere and puts his body on the line. He's been the best advocate for the game and for the Melbourne Storm for so many years."

The Storm-Sharks rivalry, which peaked when Cronulla beat Melbourne in the 2016 grand final, had its most recent chapter written at Southern Cross Group Stadium in round four.

On a night best remembered for Cameron Smith being sent to the sin bin and 33 penalties being awarded, Cronulla scored a gritty 14-4 win.

Sharks prop Matt Prior said his side is expecting a similar level of intensity this time around.

"There's a massive rivalry between the two clubs and both teams definitely get up for the game so it will be on this weekend," Prior said.

"We played with a lot of energy that game. We've done a little bit of video on them over the last few weeks so hopefully we can replicate that on that weekend."