Former Caley Jags striker Billy Mckay fired the hosts into a 39th minute lead only for Nikolay Todorov to level minutes later. Despite the half-time pause the momentum stayed with Caley Thistle and with the second period fewer than ten minutes old 19-year-old MacKay slalomed his way up the pitch and through the Staggies defence to turn the tie on its head with a smart finish.
County boss John Hughes made a triple substitution and tweaked his tactics in a bid to get his side back into the game but although they had chances to equalise, it was Neil McCann’s side who scored again, Shane Sutherland beating Ross Laidlaw three minutes from time to seal the Championship side’s passage into the next round.
Speaking after the game MacKay said: “The gaffer said to me at half-time, 'you need to run them more' and I got the perfect opportunity and thankfully when I came inside it opened right up and it went in, so I'm happy.
"I think it's been a while since we last beat them but tonight we showed that we're able to match them. We've been on a good run, I think it's the first time this year we've strung this many wins together.
"We know if we play how we have been and show the drive and determination we did tonight, then we can beat anyone on our day, and we showed that tonight.”