The Cats’ star returned to the side in Friday night's qualifying final loss to Hawthorn and looked hampered.
"I might be in a bit of doubt but I'm pretty confident I'll play," he told Fox Sports News.
When questioned if the injury had flared, he replied "no, not at all".
Former club doctor and media medical commentator Rohan White believes Johnson’s foot problem is “not a good sign” heading into the Friday night semi-final.
Johnson missed the final three rounds of the home and away season with a reported stress reaction.
"That’s not a great sign. It suggests there may be a further risk of injuring that stress reaction," Dr White told the Herald Sun.
"When doctors talk about stress injuries to bone, it’s a continuum.
"The mildest form is this stress reaction and that can turn into a stress fracture and then that can turn into a formal fracture which is often difficult to treat because often it’s the chronicity of the injury.
"If he continues to play on while it’s sore, there is a risk that stress reaction could turn into a stress fracture.
"He obviously rested for three games, so he’s had a pretty decent length of time (out) and for him to still pull up with soreness ... one would be very pessimistic about him coming up this week."
Geelong coach Chris Scott admitted Johnson’s foot problem was "going to be a problem for us".
White said Geelong would be forced to take a conservative approach.
"They will be very sensible about his management, they won’t play him if there is any risk of furthering that stress reaction."
The Cats have other concerns with Steve Motlop sustaining bruising to his right ankle.
Allen Christensen was left out of the side that lost to the Hawks due to back soreness.
"Hopefully with Christensen given the extra week off, he'll come up," Cats veteran Corey Enright told the Seven Network.
