BAGSHOT, England Owen Farrell and Ben Youngs, the halfbacks potentially key to England's assault on the 2015 World Cup, will get a taste of operating under the highest pressure in the Six Nations decider against Wales.
Flyhalf Farrell, 21, missed last week's 18-11 victory over Italy with a thigh strain but comes back in for Toby Flood, while 23-year-old Youngs will start in Cardiff having edged out Danny Care in the team named by coach Stuart Lancaster on Thursday.
Tom Croft, who appeared as a replacement against Italy 11 months after breaking his neck, starts at blindside flanker instead of James Haskell while Joe Marler is back at prop for Mako Vunipola in the two other changes from last weekend.
Victory for England on Saturday would give them their first grand slam since 2003 but they could lose and still win their second championship in three years if the defeat is by less than eight points.
Defending champions Wales, who will name their team later on Thursday, would also take the title with a seven-point win as long as England do not score three more tries than them in Saturday's match (1700GMT).
"We have come a long way through the QBE series and the Six Nations and we want to finish well on what will be a fantastic occasion in Cardiff," Lancaster said in a statement.
"Every single player, whether they are in the 23 or not this Saturday, has contributed to getting us in this position and they should be proud of that."
While Flood might consider himself unlucky to be dropped having landed six out of six penalties in England's scratchy win over the Italians, few would argue that Farrell is not ideally suited for the white-hot atmosphere of a Millennium Stadium title decider against Wales.
Cut from the same no-nonsense cloth that made his father Andy such a formidable operator in both codes and now a respected coach in his role as assistant to Lancaster, Farrell junior is mature beyond his years.
From the moment he was selected in Lancaster's first game against Scotland last year, he has looked completely at home at the highest level.
Since nailing down the flyhalf slot with his superb display against New Zealand in December's stunning victory, he has looked even more comfortable, stepping higher into the line and delivering his passes with the cold-eye of an assassin while also tackling like a flanker.
Youngs, as befits a livewire scrumhalf, is a spikier character. Two years ago he was sin-binned in Dublin for throwing the ball away as England blew their grand slam hopes in a heavy defeat.
He is a more mature player now and Lancaster is confident that he will not be put out of his stride by the noise and passion rolling down from the 82,000 predominantly Welsh crowd.
Many of the England team have never played in the stadium, by far the noisiest of the Six Nations venues and only four of Saturday's XV started the corresponding Cardiff fixture two years ago - Youngs, Chris Ashton, Dan Cole and Tom Wood.
In contrast, the majority of the Wales squad have experience of playing in grand slam deciders and many of them in a World Cup semi-final.
"A lot of our players haven't played there before, so going to that type of environment is exactly the test we want," Lancaster said this week.
"We've still got a pretty inexperienced group but they have confidence and character."
Andy Farrell, who made his professional rugby league debut for Wigan at 17 and captained Great Britain at the age of 21, also dismissed any concerns that England's young squad would not be able to deal with the occasion.
"Experience has to start somewhere and to get that first trophy it comes down to your culture and belief and togetherness to get over the line," he said. "We back ourselves there."
(Editing by Clare Fallon and Alison Wildey)