The goalscoring midfielder could be back to fitness by the end of September, but physio Mick Rathbone has warned that the incredible spring Cahill generates may have contributed to him twice suffering a broken foot.
"Tim jumps very high and unfortunately has a habit of landing on his left foot," he explained. "So like at Sheffield United when he landed and overbalanced, he cracked it.
"But with that kind of force going through it, it just caused a little injury to the site again.
"So while we're happy he'll soon be back training, it is in our minds that he has to jump and land on that."
Cahill is itching to get back into training, but the Blues are urging caution in order to avoid any recurrence.
"He's walking round with no symptoms at all now," added Rathbone. "It's so frustrating. We're looking for 6-12 weeks on that.
"Getting him back into training isn't so bad, getting him back running round isn't a problem, but getting him jumping like he does, and landing full force on the outside of his left foot, it's going to be a while before it's going to be strong enough to be able to do that."