Defences dominated an entertaining if wasteful opening period but it was 23-year-old Halfpenny who proved the difference after the break, finishing with two tries for an individual haul of 22 points.

Scotland for their part fought gamely but, in a mirror image of the last time these two sides met at the Millennium Stadium back in 2010, it was their ill discipline that cost them.

Centre Nick De Luca and full-back Rory Lamont both saw yellow after the break and Wales took full advantage as an Alex Cuthbert score preceded Halfpenny's double strike.

Andy Robinson's men did end their international try-scoring drought late on as Greig Laidlaw dived over but the damage was done by then for a Scotland side that have now lost two from two in this year's Championship.

Wales skipper Sam Warburton was a game-day withdrawal after he failed to recover in time from a dead leg picked up against Ireland last weekend leaving Aaron Shingler to come in for his first cap.

But in the opening stages Warren Gatland's men didn't seem too troubled by his absence, starting where they left off against Ireland as the effervescent Halfpenny was one successful offload away from releasing Wales for the first score inside a minute.

That began a recurring theme in the first half however as despite an open and entertaining spectacle both sides conceded possession too easily when in scoring positions.

The only scores came from the boots of Laidlaw and Halfpenny as the Welshman cancelled out the Scottish fly-half's 23rd-minute penalty with one of his own on the half-hour mark.

The final ten minutes of the half were all Scotland however but their long wait for an international try continued as Wales held firm in the face of sustained pressure from Robinson's men.

Despite failing to cross the try-line there was little doubt that Scotland went in at the interval with all the momentum but within seconds of the re-start they had surrendered it as Chris Cusiter made a hash of Rhys Priestland's high kick to concede possession deep in their 22.

And a couple of phases later Wales were over for the first try of the game as winger Cuthbert shrugged off Laidlaw's attempted tackled to dot down, Halfpenny adding the extras to make it 10-3.

And it got worse for Scotland just moments later as De Luca was sent to the sin-bin for taking out Jonathan Davies off the ball and Halfpenny once again made no mistake with the penalty.

Despite being a man down Scotland's response was almost immediate as Laidlaw reduced the arrears to 13-6 with a penalty from bang in front.

But that proved to be a false dawn as Wales gradually turned the screw with the man advantage and in the 51st minute, after spreading the ball left and then right Cuthbert put Halfpenny in for the easiest of converted scores.

Scotland were barely hanging on with a man down and their job became nigh-on impossible when Rory Lamont joined De Luca in the bin for tackling James Hook without the ball.

With a two-man advantage it was only a matter of time before Wales scored again and it was that man Halfpenny who did the damage just before the hour mark, darting over on the left after being fed by Mike Phillips.

De Luca rejoined the battle not long later and, with Lamont still in the sin bin, Scotland proceeded to enjoy their best spell of the game in search of their first try in their last five internationals.

First Stuart Hogg, who made a real impression on debut off the bench, was denied a certain try for an alleged knock-on but they didn't have to wait long as Laidlaw nipped over from close range before converting to make it 27-13.

And Robinson's men impressed late-on as they pushed for another score that would have brought them back into it but Wales held firm and will head to Twickenham in two weeks' time in search of the Triple Crown full of confidence.