Stuart Lancaster believes England will become serious contenders to win the 2015 Rugby World Cup if they can beat Wales tomorrow and win the Grand Slam.
The Millennium Stadium showdown will be a seismic title decider, with England chasing a first RBS 6 Nations clean sweep in a decade and Wales looking to retain their championship crown.
For England to triumph in those circumstances, just 14 months into their development as a team, would be a staggering achievement in its own right.
But Lancaster recognises it would also be a significant boost to England's hopes of bringing the Webb Ellis Cup back to Twickenham in 2015.
"It would give you that inner confidence and belief that you can win in big games and finals," Lancaster said.
"It's a brilliant experience for the players and it will certainly help us with that long-term plan.
"The reality is that come 2015 we're going to be playing Wales in a huge pool game. The more experience you can get of playing under the pressure of these type of games the better for the players."
England have won 12 Grand Slams but they have never sealed one in Cardiff and Lancaster feels there would be no better fixture in which to create a slice of history.
"I don't think (there is a better fixture), not in the context of where we are," Lancaster said.
"Both sides have got the chance to win the championship, so effectively it's a shootout. In that sense to go to Cardiff and try and win a Grand Slam is a great test."
England go into the match at full strength after Joe Launchbury (elbow) and Geoff Parling (shoulder) passed fitness tests yesterday to keep their places in the second row.
Lancaster has made four changes from the 18-11 win against Italy. Owen Farrell and Ben Youngs return in the half-backs, Tom Croft has replaced James Haskell at blindside flanker and Joe Marler got the nod ahead of Mako Vunipola.
Farrell missed the win against Italy with a thigh strain but he has been brought straight back, with Lancaster expecting his "unique" fly-half to thrive in the Millennium Stadium cauldron.
"He has what very few young players have particularly in the fly half position - that big game temperament and the ability to rise to the occasion," Lancaster said.
"He doesn't seem fazed by an occasion. Indeed the bigger the occasion, the more he seems to step up.
"He has been outstanding in terms of providing leadership and direction to the team. The execution of his core skills - goal-kicking, line-kicking, his passing ability, his strong defence - has been excellent."
England opened their campaign by running four tries past Scotland but their three victories over Ireland, France and Italy were down to character, resilience and defensive fortitude.
Those qualities are the bedrock of Lancaster's England side, forged through moments of adversity over the last 14 months and the reason his men go to Wales "with a quiet confidence".
"We're hard to beat because we're strong at the basics. Our set piece is strong, our defence is strong, but most importantly our attitude and desire to work for each other is strong," Lancaster said.