Celtic have won this competition in each of the last four seasons but it was the Dingwall club who booked a place in this evening's quarter-final draw after inflicting a first domestic cup defeat on the Hoops since they lost to Rangers in the 2015/16 Scottish Cup semi-final.
Ross Stewart opened the scoring from the penalty spot six minutes before half-time and defender Alex Iacovitti sealed the victory with a header in the closing minutes.
In Sunday's later game, Rangers won 4-0 away to Falkirk thanks to goals from Jermain Defoe, Calvin Bassey, Borna Barisic and James Tavernier.
