Cooper Cronk remains hopeful he will be fit to play for Sydney Roosters in the NRL Grand Final, even if he has a "fair bit of work to do" before Sunday.

Half-back Cronk suffered what was described as a "severe" shoulder injury during the Roosters' 12-4 win over South Sydney Rabbitohs in their preliminary final last weekend.

The Australia international faces a race against time to be ready to feature against former club Melbourne Storm at ANZ Stadium in Sydney, though he is making progress in his recovery.

"I'm still trying to throw a Hail Mary – hopefully it lands and we will see how we go on Sunday," Cronk told the media on Thursday.

"Most people in this room know I'm pretty diligent, pretty professional with what I do. I've gone up on that about a thousand knots this week. If there's a will, I'll find a way."

Asked if he is more confident than earlier in the week, he replied: "Yes, but how long is a piece of string?

"To be able to do some of the things to get stability, movement, range is okay, it's an improvement, but it's not enough to tackle [Melbourne duo] Jesse Bromwich or Dale Finucane, so I've got a fair bit of work to do.

"I will tell you right now, the only reason I won't play on Sunday is because I am physically incapable of doing it."

Melbourne boss Craig Bellamy knows all about Cronk's willingness to play through the pain from their time working together at the Storm.

"I know he would've been doing everything, plus, plus, plus, to be ready for Sunday," Bellamy said.

"He's a tough little rooster, excuse the pun, and I've seen him play with a lot of injuries with us. If anyone's going to do it, it's going to be Coops."

Cronk was part of the Storm side that won the 2017 Grand Final but is now hoping to prevent his old employers becoming the first team since the NRL formed in 1998 to win back-to-back titles.