Nine minutes, three goals, a last eight place secured.

The numbers added up to William Hill Scottish Cup success for Dundee United. In the end, it was as easy as, well, one, two, three.

A devastating triple whammy in the first half, which included a brace from the inventive, industrious Ryan Dow, ensured that the team from Tannadice would become only the third top flight side in today's quarter-final draw. On an afternoon of flair and flares, Jackie McNamara's men put Stranraer to the sword with a polished, professional display. Who needs Gary Mackay-Steven and Stuart Armstrong eh?

"I think professional was the best way to describe it," said the Dundee United manager, as he watched his side march on in the domestic knock-out showpiece, just a week after claiming their spot in the Scottish League Cup final. "It's important that players like Ryan stand up and show they are ready to take the shirt and stay in the team with Stuart and Gary now gone. For me, Dow changed the game for us in the semi-final last week, he was great. He's found his way and I have great belief in him as a player. We have great faith in the rest of the boys in the squad."

The hosts started with plenty of zeal and were determined not to roll out the welcome mat to their guests from the City of Discovery as they got plenty of tackles in and gave the visitors little time or space to settle in.

Stranraer, the SPFL League One leaders, were making life about as comfortable as a February dook in Loch Ryan for their Premiership opponents but in terms of goalmouth incident there wasn't much to rouse the senses. Indeed, the only real action in the six yard box in the opening 20 minutes was provided by a flare that was hurled on to the pitch from the visiting supporters.

A steward was thrust into action and covered the offending item with a bucket - presumably Oor Wullie was in the United end and offered his services - and for a baffling spell, this silver clump of hardware became something of a celebrity figure as play was halted while we waited for the flare to be snuffed out. Had Willie Collum been the referee, he probably would've booked the bucket for time wasting.

Not long after this flare-induced palaver, the visitors took charge in ruthless fashion. In the 22nd minute, Sean Winter, completely oblivious to the presence of the lurking Erskine, was woefully short with an attempted pass back to Craig Pettigrew and Erskine darted in and poked a tidy finish beyond the advancing David Mitchell.

It was a morale sapping goal to concede but Stranraer almost received the ultimate injection of confidence just three minutes later. A corner from the right was headed towards his own goal by Callum Morris but Radoslaw Cierzniak, the Dundee United keeper, spared his team-mate with an instinctive save.

The importance of that block was highlighted moments later as the visitors doubled their lead. Stranraer's defensive dithering would cost them dearly again. Scott Rumsby, hesitant and indecisive, failed to deal with a punt down the left flank and Dow seized his moment, jinking in on goal and lifting a nice finish over Mitchell.

With the hosts now wheezing forlornly on the ropes, United floored them with a third just after the half hour which was delightfully simple in its clinical majesty.

Nadir Ciftci threaded a superb pass right through the heart of the Stranraer rearguard and Dow trotted in, rounded the keeper and trundled the ball into the empty net.

The last time these sides had met at at Stair Park in 2012, United ran out 5-0 winners. Given the calamitous way things were developing, the cursing, muttering locals must have been fearing an even more desperate humping.

The half-time Bovril might have tasted a little better, mind you, had Stephen Stirling's header not been nodded off the line by Ryan McGowan.

Down but not out, Stranraer produced a spirited second half showing in what became a largely scrappy tussle and Chris Aitken and Grant Gallagher both threatened. It was United, last year's beaten finalists, who came closest to adding to the goals tally though as Charlie Telfer's curling free-kick in the dying embers produced a flying save from Mitchell.

"They were clinical," said Stephen Aitken, the Stranaer manager. "It was disappointing the way we gave them the first two goals. We laid them on a plate. But we showed a lot of endeavour and competed well. At 3-0 it could have gone four, five or six but we knuckled down and tried to get something out of it."