Craig Brown made just one change for this one, Mitch Megginson coming back into the starting XI in place of Rory Fallon who dropped to the bench.
There was an early blow for the Dons when Rory McArdle was booked inside 4 minutes for a challenge on Shane Sutherland on the edge of the box. Caley made nothing of the resultant free kick and when the Dons broke up field, it was McArdle who's cross had to be tipped behind by Jonny Tuffey. From the corner kick, the ball fell to Kari Arnason but he stabbed the ball wide of the post.
On 10 minutes the home side found themselves behind. Billy McKay rounded the floundering Jason Brown and set up Gregory Tade to slot the ball into the net to give the visitors the lead. The goal gave Caley huge confidence and they continued to press the Dons and dominated for long spells.
But The Dons tried to hit back on 12 minutes but were denied what looked to many of those inside Pittodrie to be a stonewall penalty. Mitch Megginson crossed into the box and the ball appeared to hit the hand of a Caley Thistle defender but both the referee and linesman refused the claims- to the annoyance of the Red Army. That decision would have been all the more harsh had Kari Arnason not blocked an effort off the line on 22 minutes when Caley continued to threaten the home goal.
Inverness had another chance soon after but Tudur Jones' shot went well wide after Arnason couldn't stretch far enough to gather a McArdle clearance.
Gavin Rae was then the second Dons player to be booked in a frustrating first spell when he tackled Tade just inside the Inverness half on 36 minutes and referee Finnie deemed it to be worthy of a caution.
The Ref was then the centre of attention just before half time when he was called over to speak to Caley boss Terry Butcher- irate that a challenge by Arnason went unpunished. That was the last real action of a disappointing first half for the home side.
A half time substitution for the Dons saw Peter Pawlett replace Kari Arnason as the Dons tried to recover their one goal deficit and they began the second half much better than the opening period, butScott Vernon was unable to reach a decent cross from the left as the ball sailed over his head. Moments later Chris Clark crossed a superb ball into the box but Ross Tokley was there to clear for the visitors.
Caley player Josh Meekings was then sent off for two bookable offences within a few minutes, the second of which saw the player miss time a tackle on Pawlett, who was setting off on a run down the left flank. With the home side now facing 10 men and desperate to get back into the game, Mohammed Chalali replaced Chris Clark on 57 minutes. The Algerian u23 international had his first chance minutes later but shot miles wide when set up by Gavin Rae in the box.
Top scorer Vernon, who had a relatively quiet afternoon, was at the centre of some neat exchanges in midfield when he slid the ball to Chalali in the Dons best move of the day but Chalali couldn't capitalise and the Inverness defence cleared for a throw.
With no sign a goal was coming, Cup quarter final hero Rory Fallon was called for from the bench and he replaced Mitch Megginson on 68 minutes. And Fallon nearly had an instant impact when Peter Pawlett swung in a super cross but the New Zealander's resultant header was straight at Tuffey.
On 70 minutes a Ryan Jack shot went miles over the bar and a short time later Scott Vernon forced Tuffey into a save as the Dons continued to press without making their dominance count.
Referee Finnie was then called over to the touchline again- but this time it was Maurice Malpas who was in trouble and the ref wasted no time in sending the former Dundee United player to the stand.
A further chance fell to Chalali but his shot was beaten away well by Tuffey, who had been a late replacement for former Don Ryan Esson who injured himself in the warm up. When Clark Robertson's cross went well over the head of Rory Fallon you just felt it wasn't going to be the Dons day and despite a superb lobbed ball from Vernon setting Pawlett up on 85 minutes which the youngster smashed into the side netting, the Dons couldn't get themselves back into it.
Chalali was then booked for dissent in the final few moments as Caley held on to take the 3 points on the long journey back to the Highlands and consign the Dons to a second consecutive defeat.