Leigh Halfpenny contributed 22 points as an improved second-half display saw Wales put themselves on course for a potential Triple Crown with a 27-13 victory over Scotland at the Millennium Stadium.

A penalty apiece from Halfpenny and Greig Laidlaw had seen the scores locked at 3-3 at the break but Alex Cuthbert crossed early in the second half to give Wales the lead.

Scotland then paid the price for yellow cards dished out to Nick De Luca and Rory Lamont as Halfpenny scored a brace of converted tries and added a penalty with the Scots light on numbers.

Scotland finished strongly and Laidlaw, who had earlier kicked his second penalty, registered their first try in five games but it was too little too late.

Laidlaw kicked a 22nd-minute penalty from close range but Halfpenny, retained as first-choice goalkicker following his late heroics in Dublin, drew Wales level 10 minutes before half-time through an effortless strike from 40 metres.

The home side suffered a major blow when wing George North limped off nursing an ankle injury, being replaced by James Hook, with Halfpenny taking North's wing slot.

Wales coach Warren Gatland clearly gave his team a severe half-time lecture, and it had the desired effect as Scotland unravelled in alarming fashion. Scrum-half Chris Cusiter made a hash of gathering the kick-off, and Wales pinned Scotland back from an attacking lineout, working the attacking angles until Hook sent Cuthbert galloping over.

Halfpenny converted, and Scotland kept their finger on the self-destruct button when De Luca tackled Jonathan Davies without the ball and referee Romain Poite yellow-carded him on assistant Simon McDowell's recommendation.

Laidlaw briefly reduced Scotland's deficit through his second penalty, but rampant Wales then struck again after more patient attacking play saw Halfpenny score, and then he struck again just five minutes later.

Scotland were at sixes and sevens, and with Halfpenny also kicking 12 points, Wales had done the damage - despite a late yellow card for Jenkins - and they will head to Twickenham in 13 days' time quietly confident of completing stage three in a possible third Grand Slam season in eight campaigns.