England full-back Ben Foden believes that a Grand Slam success would be the ideal confidence boost ahead of the World Cup.
England are the only side left unbeaten in the RBS Six Nations following wins over Wales, Italy and France.
Martin Johnson's side next face Scotland at Twickenham on March 13, followed by a trip to Dublin to take on Ireland in the tournament finale.
And the 25-year-old Foden, a try-scorer in the 17-9 victory over France, claims victory in the last two games will throw down a marker to England's World Cup rivals.
Foden told Sky Sports News: "It would be massive for us, for confidence, taking that forward to the World Cup.
"It puts yourself in the environment, under the pressure of competing at high-level competition.
"To go to Ireland and win there would be a massive achievement and to beat all the northern-hemisphere teams and say 'we're No.1 in the northern hemisphere' come the World Cup would really set a marker.
"Obviously we had a little bit of success in the autumn internationals against the southern-hemisphere teams. Everything's building nicely towards the World Cup."