Sean Lamont believes Scotland will need to produce a perfect performance against Wales on Saturday to claim a third successive Six Nations win.
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, 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."
Scotland's defensive coach Matt Taylor also warned the team simply cannot afford to take any more chances with Wales' powerful strike runners like George North and Alex Cuthbert.
He said: "As a defensive coach, there were a number of situations against Ireland I was unhappy with, such as players falling off tackles.
"But the one thing I will say was that our ability to scramble and ability to get back and regroup was fantastic. That says a lot about the group and their commitment to one another.
"We have had to work hard with that. It hasn't happened overnight. It's been a process since we got here in the autumn. The guys are starting to buy into the system and it's paying dividends.
"But the scramble is not the type of thing we can do game after game.
"Against Wales, we now need to make sure we make those one-on-one tackles, especially against their big guys, or we'll put ourselves under a lot of stress."
Scotland will now hope to marry their defensive prowess with the attacking threat that brought six touchdowns in their opening two games and notch up three successive victories for the first time since 1996.
Lamont, 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."
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