Although the home sided began the stronger forcing a succession of early corners, it was the Dingwall side that took the lead in the 16th minute when the impressive Craig GUNN raced down the right before firing in a shot from a seemingly impossible angle that sneaked in at Greg Kelly's near post.
Within two minutes parity was restored when a long David Donald throw from the left caused panic in the visitors defence and after a scramble, Willy John KIELY reacted quickest to hook the ball past Joe Malin for the equaliser.
Seven minutes later, the Dons tool the lead when Chris Maguire's powerful run down the right ended with a cross that was met first time by MCINNES who gave Malin no chance from eighteen yards.
Far from being disheartened, County rolled up their sleeves and immediately won a free kick wide on the left. Kevin Duguid's high ball looked to be Kelly's all the way but he somehow managed to let the ball squirm free and Neal HOOKS took full advantage to force the ball over the line.
Both keepers were called upon to make good saves before the interval and after the quickfire goal action, the second half was almost inevitably a much tamer affair with clear scoring opportunities at a premium.
It looked like it would take a special effort to decide the tie and that is exactly what happened when, in the 71st minute a Neil McVitie goal kick was picked up in the middle of the park by MCINNES. There looked to be not much on for the midfielder but his mazy run left a succession of defenders trailing in his wake before firing a fine shot beyond Malin and into the net to complete the scoring.