Ross County 6-2 Dundee United

Chris Routis opened the scoring with a spectacular strike

Ross County gained revenge for last year's Scottish Cup exit to Dundee United with a crushing fourth-round victory at a foggy Dingwall.

Chris Routis' stunning dipping volley put the hosts ahead before Tony Andreu's sweet side-footed equaliser.

But Paul Quinn's header put County back in front and further strikes from Tim Chow and Liam Boyce made it 4-1 before Andreu's second gave United hope.

But Routis grabbed his second and Jim O'Brien's late goal made it a rout.

The second half was always going to struggle to match the excitement of a thrilling first period featuring six goals.

Coutis gave County the ideal start when he controlled a corner from the left on the edge of the area and sent a right-footed volley across Cammy Bell into the top left corner.

But United replied within eight minutes after good work down the left from Tope Obadeyi, whose cross was met first time, on the volley, by Andreu on the edge of the box with the inside of his right foot.

Parity lasted just two minutes, however, as Cammy Bell could only beat Alex Schalk's free-kick into the air and Quinn nodded the home side back in front.

A Routis run and shot down the left paved the way for County's third, Chow's low strike beating Bell through the Dingwall mist.

Boyce appeared to have settled the outcome inside half an hour when he cut inside Jamie Robson and tucked away a left-footed finish for his 14th goal of the season.

But a poor back-pass from Coutis allowed the on-loan Andreu to stroke home his second just before half-time to keep United in it.

United dominated on the resumption without reward, and County, who were beaten 3-2 by United in Dingwall in last year's quarter-finals, might have stretched their lead through Schalk's header.

But with 14 minutes left Coutis finished off a flowing move - at the second attempt - after being set up by substitute O'Brien.

The winger then grabbed a debut goal himself in the final minute from Boyce's pass.