Midfielder Craig Bryson’s ankle is set to be scanned to assess if there is any damage from a horror tackle in the 1-1 draw at St Johnstone.
Saints’ Murray Davidson received a straight red from referee Kevin Clancy for lunging into a rash challenge on Bryson’s right ankle.
Summer signing Bryson has already missed much of the season so far with two separate ankle injuries.
Bryson signed on at Pittodrie in the summer still recuperating from an ankle injury sustained at former club Derby County before the end of the English season.
Despite featuring as a substitute in the 1-1 Europa League draw to Chikhura Sachkhere in Georgia, the midfielder did not make his first start until a League Cup tie at Dundee on August 18.
Just a few games after he suffered an injury to his other ankle that ruled him out for a month.
McInnes said: “Both ankles have been a bit of an issue for Craig, one in particular.
“The first thought was that he took a sore one again.
“Thankfully Craig was able to play on but we will probably need to get that imaged and see how that plays out.”
Davidson’s dismissal was the first of two straight reds for St Johnstone in just four minutes.
Substitute Callum Hendry was also sent off for a lunge on midfielder Lewis Ferguson.
Aberdeen were unable to make the two-man advantage count as they dropped points to the side bottom of the Premiership.
McInnes said: “There was a mistake to give them their opportunity to score.
“We have always been good in previous seasons of showing our experience, know how and quality to see a game out.
“I am disappointed we didn’t do that.
“After our first half performance I was looking for better.
“We went with two strikers and two wingers and tried to ask the question more of them defensively.
“I don’t think we got enough service to our front two or they caused them too many problems.”