Gardiner, 31, strained a hamstring late in the second quarter against Collingwood on the weekend and failed to return to the field after half time.
Lyon said the Saints would wait until the last minute to make a call but looked likely to be forced into making a change, with Gardiner rated as less than a 25 per cent chance of playing.
“It’s a new set of circumstances, a new set of 22 it looks like for us with Michael unfortunately,” he told One HD’s One Week At A Time on Monday night.
“We’ve got a really close relationship, he’s a great person and he wants a premiership medallion around his neck.
“He’s played in a number of grand finals and what he’s achieved since he’s been at the Saints and what he’s brought to the club ... he’s a significant contributor and an ally in my coaching.
“He’s been remarkable in helping me drive the group.
“We’ll give him every opportunity to get up but we know he’ll have full support for everyone that runs down the race if that doesn’t occur.”
Gardiner will be painfully unlucky to miss given he has played in two grand finals (2005 at West Coast and 2009 at St Kilda) before the weekend’s draw for no wins.
Lyon said Ben McEvoy, who appeared the logical replacement for Gardiner, wasn’t the only option the Saints had.
“On balance, [Justin] Koschitzke stays a permanent ruck and we bring in Rhys Stanley, who was really critical in that period without [Nick] Riewoldt there,” he said.
“[Sam] Gilbert gave us that speed and agility [up forward] so he might be something we look at there ... [or] Jack Steven, a lightning small forward, who’s up and about again.
“They’re the options, but we’re still gathering ourselves a little bit and that final match committee where everyone pours in their ideas and we thrash it out, we’ll come up with the 22 later in the week.”
Lyon said midfielders Nick Dal Santo, Jason Gram and Clint Jones, who were all underwhelming against Collingwood, were “physically fine” and expected to play.
“Gram has already contacted me and said he was really committed to lifting his work rate,” he said.
“I expect [Dal Santo] and Jason and Clint to be better for us.”
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