Danny Williams' first Inverness goal gave Caley Thistle a deserved first win in six games against Aberdeen.
The Englishman hit a fierce 10-yard shot in off the bar in the 22nd minute to earn manager John Hughes his second victory in charge.
Aberdeen had plenty of set-piece opportunities but lacked invention in open play at Pittodrie.
And the visitors almost extended their lead when Graeme Shinnie's late curled shot hit the foot of the post.
That chance on the break summed up the story of the game, with Inverness creating the more clear-cut chances by far, despite the Dons' high count of corners and free-kick opportunities.
Over 12,000 fans turned out to see Aberdeen stutter in a match they were favourites to win on recent form.
The first signs of Caley Thistle's threat from the wings came when Billy McKay almost connected with Aaron Doran's low cross from the right, but that preceded a 15-minute spell of Aberdeen superiority.
Niall McGinn and Barry Robson caught Inverness sleeping with a quick corner and Robson's cross is arrived at the head of striker Scott Vernon, who could not direct his effort on target.
The Dons won themselves 10 first-half corners and with the delivery of set-piece expert Robson, most would expect one to lead to the breakthrough.
However, a combination of wayward headers and solid Inverness defending frustrated the hosts and a clever counter-attack brought the Highlanders the lead.
Doran, again scampering down the right, sent in another testing delivery which McKay touched on to Williams, who netted his first Caley Thistle goal emphatically with a thumped left-footer that found the top corner via the crossbar.
Williams, signed from Kendal Town in the summer, proved to be a constant menace, popping up on both flanks to trouble Aberdeen.
The Englishman played in Doran to test Dons goalkeeper Jamie Langfield before again showing his creativity by rolling the ball across the six-yard box - a pass which was only just missed by the stretching McKay.
And he picked up where he left off at the start of the second half, centring for a McKay stab at goal that required a good block by Mark Reynolds.
Aberdeen's set-piece woes continued as Russell Anderson bulleted another header over the top of Dean Brill's goal.
Derek McInnes introduced winger Jonny Hayes and forward Josh Magennis to provide fresh energy up, but the Dons' best chance of the match came from the boot of Willo Flood.
The ball ricocheted to the Irish midfielder in the same position he netted his winner against Hibs, and his dipping half-volley was turned over by Brill.
Shinnie's effort off the upright was followed by McKay whizzing a low drive by the post as Inverness searched for a second.
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