The youngster hopes to be back next month, but Stoke are not counting their chickens as he has already suffered one or two setbacks on the road to recovery.
Coates told BBC Radio Stoke: "We're keeping our fingers crossed because we've had a few false dawns with him. Let's hope he'll be playing again soon – we're hopeful it's finally on the mend."
However, the form of Grant has been a huge bonus as the 33-year-old has impressed since his loan switch from Championship outfit Derby County in the summer.
"He's put in some great performances," Coates added. "He's done remarkably well. He's come in and had an opportunity to play at a higher level and he must be as delighted as we are - it's a great story."