And Geelong captain Patrick Dangerfield will eye his return from a calf injury against West Coast but appears no guarantee to feature.
Gunston pulled up sore in his right hamstring in the third quarter of Hawthorn's epic one-point Easter Monday win over Geelong, but after having treatment he played out the game and kicked the winning point at the death.
The 34-year-old is expected to have scans to rule out any serious strain ahead of Saturday's blockbuster at Adelaide Oval.
"Didn't look great, did it?" coach Sam Mitchell said.
"I saw him lead out, and I saw him grab the hammy, and I was thinking, 'Oh that's not ideal'. And then they got him off, and they said he was fine, and he came back on.
"I haven't had a full medical update, but the fact he came back on, I guess, having done a couple of hammies before, it's pretty unlikely that he's actually done that.
"So I'll have fingers crossed, but we won't know more for a couple of days, I'd imagine."
Gunston earlier played down the incident as "just cramp".
Mitchell said he'd been told co-captain Sicily had suffered "just a stinger" in the fourth quarter before returning to play a pivotal role.
"I thought I blew my shoulder out again," Sicily told the Seven Network.
"I've got a bit of PTSD with these two shoulders from the last two years so I was a little bit emotional but it's settled and it's completely fine.
"It feels like it's fine structurally, just a bit bruised."
Dangerfield told SEN pre-match his calf was good and "ready to go" while Scott indicated he had been close to selection on Monday.
"I hesitate to say, 'Yes, he could play, but we're choosing not to' - it's not as simple as that," Scott said.
"But I think we can give you some comfort that he's put some good training together and if there's a battle between, 'Is he right to play, or should we invest a little bit more in sort of later on in the season?' - that battle is winning a little bit at the moment.
"But he's going well. Certainly come and ask me the question, 'What the hell's going on?' if he doesn't play in the next couple of weeks."
Geelong could err on the side of caution for Sunday given they face the unbeaten Western Bulldogs the following Friday.
Scott said spearhead Jeremy Cameron had suffered a knock to his body but the arm he broke in last year's grand final was fine.
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