Rhys Priestland has no doubt that Wales' defensive qualities will need to be fully on show in Saturday's RBS 6 Nations clash against Ireland (2.30pm).
Wales conceded three tries to Ireland during the opening game of last season's tournament - and then performed defensive shut-outs in successive victories over France, Italy, Scotland and England.
"Defensively, we are going to have to be at our best, and we need to improve with the ball in hand from last week, but defences win you championships," Wales fly-half Priestland said.
"It will be a massive test, defensively, to keep them quiet.
"They are the rivals we know best because both countries have four teams in the (RaboDirect) PRO12 and come up against each other quite often. We are familiar with the way we both play."
Although it is only the second weekend of a competition that does not reach its finale until mid-March, the victors this weekend will seriously enhance their championship credentials.
Both teams won in round one - Wales beating Italy 23-15 and Ireland overpowering Scotland 28-6 - to set up a potentially-thrilling Dublin encounter.
Wales have triumphed in three of the last four meetings against Ireland, including a 2011 World Cup quarter-final success, but Brian O'Driscoll inspired an Irish win on Welsh soil 12 months ago.
"It is a massive challenge, and there is a buzz about the place looking forward to combating whatever Ireland throw at us," Priestland added.
"We are under no illusions about how difficult it is going to be, the toughest challenge we will face in the Six Nations, maybe"
"It will be hostile there and they will be desperate to stop us going for the third title (in succession), and we are desperate to win it.
"We are looking to test ourselves against a very good Irish team which could have beaten the All Blacks last year. We are under no illusions about how difficult it is going to be, the toughest challenge we will face in the Six Nations, maybe.
"The way they have been speaking about the game and the way they should have beaten the All Blacks means they are on a massive high, and it could possibly be our toughest challenge."
The potential individual contests are numerous - Priestland against Jonathan Sexton, Mike Phillips versus Conor Murray, Adam Jones against Cian Healy and Sam Warburton opposite Chris Henry among the pick of those battles - suggesting it could prove a Test match that comfortably lives up to expectations.
"He (Sexton) is a Lions 10 and a fantastic player," Priestland said.
"I have played against him a few times and we know as a squad how dangerous he can be, especially with the understanding he has with O'Driscoll.
"Both back-lines are very talented. Everyone knows how dangerous and powerful our backs can be. Their back-line is different to ours, and who is to say which is best."
Live television coverage of Ireland v Wales and Scotland v England from 13:30 on Saturday 8 February, and France v Italy from 14:30 on Sunday 9 February on RTÉ Two and RTE.ie (Ireland only). Live radio coverage on Saturday Sport (14:00) and Sunday Sport (14:00) on RTÉ Radio 1 and RTÉ.ie (Worldwide).