County looked a shadow of the side that beat their local rivals on New Year's Day as Inverness ran out deserved winners.
County forced two free kicks in dangerous positions in the opening skirmishes but it was the visitors who took the lead after just seven minutes.
County had claims for a penalty turned down 10 minutes later when Jordan Slew's shot inside the box appeared to be handled by Gary Warren but referee Calum Murray was having none of it.
At the other end Graeme Shinnie charged past Brittain on his left but his angled drive just cleared the far post.
There was little in the way of goalmouth action as both teams battled for supremacy in the middle of the park.
Yoann Arquin tried to prise open the Caley Thistle defence with a pass to Alex Cooper but his first touch was poor and the visitors broke upfield but Richie Foran fired a shot well wide of the far post.
County were enjoying their fair share of pressure without doing too much with it and they were caught out again five minutes from the break.
Shinnie won the ball off Slew, drove forward and squared the ball for McKay who swept the ball into the corner of from 12 yards.
Inverness were going all out for a third and Doran had a shot charged down by Yann Songo'o in front of goal.
Arquin and Slew combined on the edge of the area in the opening minute of the second half but Slew lost his balance at the vital moment.
County had a great chance to pull one back in the 49th minute when Michael Tidser got on the end of a Cooper cross but his point-blank shot was parried by Brill.
The home side continued to push forward and Filip Kiss tried his luck from 25 yards in the 56th minute but his effort flew narrowly past the upright.
It was mostly County at that stage but in a breakaway move on the hour mark, Doran raced on to a long through ball from McKay but Erik Cikos got in a timely tackle just as the Inverness man was about to shoot.
But it was all over as a contest in the 77th minute when Doran slipped the ball through for substitute Marley Watkins and he coolly drilled the ball into the far corner of the net.
- Sports & Recreation
- Aaron Doran
- Jordan Slew