Only a perfect Scotland performance will be good enough to secure a third successive RBS 6 Nations win, according to centre Sean Lamont.

Scotland have so far followed up their opening-day defeat to England with wins over Italy and Ireland, but all three games have seen dips in performance in crucial areas.

At Twickenham the Scots suffered at the breakdown and paid the price in a 38-18 defeat, while Italy lost out 34-10 even though the four-try hosts were far from perfect at Murrayfield.

Scotland were frantic in defence at times against Ireland as a combination of an astonishing possession count for the visitors, teetering on 80 per cent during the first half, and a number of missed tackles saw their opponents bear down on the score-line.

It was only good fortune, as Lamont claimed today, that prevented them from crossing over before Greig Laidlaw booted four second-half penalties to secure an unlikely 12-8 triumph.

With Wales the visitors to Murrayfield today, Glasgow man Lamont has warned Scotland cannot afford to rely on luck again.

He said: "Against Ireland, we were lucky at times. They bombed a couple of chances. But I want it to be more than just luck this weekend. I want it to be us doing everything right - us making no errors. That's the only way we are going to beat Wales."

Lamont is still feeling the pain of last year's wooden spoon finish, added: "We don't want this to be a flash in the pan, we want this to be something that will snowball. We've got to keep it going for everybody's sake.

"This is certainly a lot less stressful than this time last year, that's for sure. Rugby is always a damn sight more bearable when you are winning than when you are losing every week. It's not a nice sport when you are being beaten all the time.

"Everything hurts more, injuries take longer to heal up - or at least that's the way it feels. So we are in a good place right now. But nothing counts unless you can back it up."

Wales star Leigh Halfpenny is one of the dangermen in Rob Howley's lineup, particularly for Scotland. The full-back's tally of 32 points against them in just three appearances features four tries, including a double last season.

Since taking over from an out-of-sorts Rhys Priestland as principal goalkicker midway through Wales' 2012 RBS 6 Nations opener against Ireland, Halfpenny has amassed 184 points in 15 Tests.

If the 24-year-old maintains his current strike rate, he will overtake Paul Thorburn as Wales' fourth all-time highest points scorer behind Neil Jenkins, Stephen Jones and James Hook later this year. On present form, a British and Irish Lions Test place also beckons against Australia in June.

"I am pleased with how things have been going," said Halfpenny, whose head-to-head with Scotland full-back Stuart Hogg tomorrow could easily pass as a Lions Test team audition.

"I've been working hard, but I still have to keep working hard and still look to keep on improving. I want to get my hands on the ball more and come into the line more. But overall, I'm pretty pleased with how the kicking has been going. I need to keep working on that and keep that going.

"The last two games (against France and Italy) have been pretty tight games, with not much attack. It has been low-risk rugby, playing more territory and putting pressure on the opposition to attack.

"Hopefully, we can get plenty of ball out wide and show a bit more of our attacking game. We all want to get the ball in our hands and we want to score tries - there is no better feeling than that. The last two games we've had to find a way to win, to grind wins out.

"In Italy, there was no way we could play expansive rugby because the conditions didn't allow us to. But we adapted our game, and I think that was the pleasing thing out there. We turned up, it was hammering down with rain and we were able to talk about it and execute a different game-plan."

Those hard-fought victories in Paris and Rome have given Wales a chance of successfully defending the Six Nations title, although Grand Slam-chasing England remain clear favourites.

If they win today - Wales are unbeaten at Murrayfield since 2007 and have defeated Scotland five times in succession - it would set up a Millennium Stadium showdown with England tomorrow week.

Halfpenny rates Hogg highly, but the Scottish discovery will need to get past his opposite number first if he intends breaking down a Welsh defence that has not conceded a try in almost 200 minutes of Six Nations action.

It is a task that memorably proved beyond England wing David Strettle at Twickenham last season, when Halfpenny's fearless last-ditch tackle kept Wales on course for the Grand Slam.

And there was further evidence of his defensive bravery against Australia earlier this season when he tried to stem a late Wallabies counter-attack. Australia won the game - Halfpenny ended up being detained overnight in hospital.

"I love the challenge - it is something I've always relished since I was a kid," he said, of his attitude to defensive duties. I've always been the smallest in the team. Everyone else has always been bigger than me, and yet I've always enjoyed the physical side of the game, the tackling.

"I see it as a challenge. They (opponents) are probably thinking 'I am bigger than you, I am going to run over the top of you'. But I am looking at them and thinking 'no chance, you are not passing me'.

"Shaun Edwards (Wales defence coach) has brought that part of my game on a hell of a lot, and it's something I am looking to keep going, but my mum has always got her face behind her hands. She can't watch at all."

Wales' recent results have seen them halt a demoralising run of eight successive defeats. Victory this weekend would secure a Welsh record five championship away wins on the bounce and an 11th triumph from their last 13 Six Nations starts.

"It is difficult when you have to come in the week after a loss for eight games," Halfpenny added. "You can perhaps get into a losing habit. But we've found a way to win, like we did in the (2011) World Cup and the last Six Nations.

"The games against Australia last summer were so frustrating - we lost a couple of games late on against them - and the autumn series this season was poor. We wanted to come into the Six Nations and bounce back from that. We wanted to do it for ourselves and for the country.

"The fact that we've won a couple of games, confidence and momentum comes through that. The spirits are up."

Live RBS 6 Nations coverage on RTÉ Two and RTÉ.ie (Ireland only) from 2pm on Saturday 9 March (Ireland v France 5pm) and 2.30pm on Sunday 10 March.

Live radio coverage of Ireland v France on Saturday Sport on RTÉ Radio 1 and RTÉ.ie (Worldwide) from 2pm.