Slater was charged with a grade-one offence for his hit on Cronulla's Sosaia Feki on Friday night, meaning he will miss one match even with an early guilty plea.

The retiring superstar was penalised for the incident but not placed on report on Friday night, after he came across in cover to save a try and put Feki into touch.

Melbourne are confident they will beat the charge and began preparing their defence as early as Friday night, and will push for the case to be brought forward to Monday if the NRL deems it possible.

"It's pretty hard to make a conventional tackle when you're going across at top speed trying to save a try like that," Slater said after Friday night's win.

"I was going across in desperation to try and save the try. I was at top speed, Sosaia Feki was at top speed.

"I thought he was going to step back inside me hence why I was upright. It's hard to get your head down for a shoulder tackle position.

"It was just an unfortunate collision."

Melbourne captain Cameron Smith also missed the Storm's 2008 grand final loss to Manly through suspension, while Kiwi hooker Issac Luke is the last big name to have missed a decider due to a ban with South Sydney in 2014.

The loss of Slater will be a massive blow to the Storm regardless of whether they play the Sydney Roosters or Souths, given he is still close to his best despite being 317 games into his NRL career.

The fullback scored two tries and set up another in Friday night's 22-6 preliminary final win over the Sharks at AAMI Park, and also saved two tries at the back - with one being the hit on Feki.

If he is suspended, youngster Jahrome Hughes would likely come in for just his 18th NRL match and first finals clash. Scott Drinkwater and Ryley Jacks would form less likely options.

The charge comes after Sharks coach Shane Flanagan declared on Friday night he should be free to play in the decider and stand-in captain Luke Lewis questioned how he could be suspended at all.

"What do you want him to do?" Lewis said.

"He's one of the best defensive fullbacks in the game and you have to stop a try and put your body on the line.

"If someone was to miss a game for something like that, I don't know what our game would be coming to. It's a contact sport.

Australian Associated Press