Ross County manager Jim McIntyre was delighted with the clinical way his players booked their place in the last 16 of the Scottish Cup despite a couple of lapses against Dundee United. County found themselves 4-1 up with goals from Christopher Routis, Paul Quinn, Tim Chow and Liam Boyce, before Tony Andreu's second goal of the match on the stroke of half-time gave the visitors hope.But two late goals from Routis and debutant Jim O'Brien ended the tie as a contest.McIntyre said: "We played some great stuff, especially in the first half, and got into a commanding lead. The only blip was getting a bit sloppy."So that was disappointing and it gives them the hope there's a chance of getting back into it."In the second half we had to weather pressure, as you have to against any team. You never have it all your own way, but I thought we defended quite well."And, despite the healthy margin of victory, McIntyre felt there were more goals in his side.He said: "There were a lot of balls into the box we got headers on and a few corners, but I always felt there were more goals there to be had for us, especially with Alex Schalk's pace against their two centre-backs with United pushing their full-backs on."McIntyre was delighted with the contribution of all three substitutes."The new recruits did well and I thought all the subs did well," he said of O'Brien, Reghan Tumilty and Milan Lalkovic, "Young Reghan was excellent and deserves special mention."Jim O'Brien and Milan Lalkovic will definitely provide that spark. They have that quality. I'm excited when I see them get on the ball. They look to make things happen and are both very dynamic in terms of wanting to get at people to hurt people."It'll take a few weeks to get up to speed in what's expected of them in terms of our team shape, but they made a good start."United manager Ray McKinnon felt the loss of a second goal so quickly after drawing level was crucial.He said: "It was disappointing to lose the second goal when we'd got back to 1-1 so quickly."We gave away a cheap free-kick and didn't deal with the second phase after Cammy Bell saved the free-kick. That was disappointing - as were the next two goals."McKinnon rued the fact his side did not score when they were on top early in the second half."I thought at 4-2 it was important we came out in the second half and upped the intensity and I thought we did that for 30 minutes," he said. "We were very good in the second half, but just couldn't get that third goal."Had we done that, it would have been a different game - and then we got caught with the sucker-punch. We just couldn't get that clear-cut chance."Overall, it is always disappointing to lose that amount of goals. Ross County probably deserved it on the day and we need to take it on the chin."The scoreline probably paints a different picture, but we have to accept that's what the scoreline says."