Aberdeen today confirmed keeper Joe Lewis will undergo surgery having suffered knee cartilage damage in the 2-0 loss to Rangers.
That is expected to rule Lewis out for at least a month to eight weeks.
It was initially feared the 30-year-old had suffered a leg break in the collision with Rangers’ attacker Josh Windass.
Lewis was stretchered off and then rushed to hospital in Glasgow where a scan confirmed there was no leg break.
However a subsequent MRI scan on Thursday night has confirmed cartilage damage.
Dons boss Derek McInnes said: “On the back of the MRI scan on Thursday night we got the results that there was cartilage damage to Joe’s knee.
“It is quite a significant injury and he will get the operation at the beginning of next week.
“That will unfortunately keep Joe out for a period of time.”