Dumbarton roared back from being a goal behind to lift the spoils and heap further pressure on under-fire Inverness manager John Robertson.
It was a history making occasion yesterday, a first ever league clash between these sides, and the first in any competition for over 11 years.
The Highlanders got the start they craved when Liam Polworth sent Connor Bell through on the left to slide the ball past goalkeeper Scott Gallacher from 15 yards.
The Sons levelled two minutes after the restart. Tom Walsh crossed from the left, Mark Stewart head flicked on and Dimitrios Froxylias volleyed home from 10-yards.
The winner came in 62 minutes when a 20-yard curling free-kick by Froxylias was palmed out by goalkeeper Owain Fon-Williams, but Sam Wardrop was sharp to react and crash the ball in on the angle six yards out.
Caley were reduced to 10 men in 79 minutes when Gary Warren was red-carded for diving, having previously been booked.