England have selected Saracens' Owen Farrell at fly-half and Sam Burgess at inside centre for Saturday's crunch World Cup showdown with Wales at Twickenham.

George Ford has been demoted as first choice playmaker - a position held since last autumn - to make room for Farrell despite showing solid form during the warm-up matches and the 35-11 victory over Fiji.

England have completed a radical overhaul of their midfield after Jonathan Joseph was ruled out against Wales with a chest injury by picking Burgess and moving Brad Barritt to outside centre.

The Farrell-Burgess-Barritt combination - the most muscular trio available to head coach Stuart Lancaster - has been chosen in anticipation of the looming gainline war at Twickenham.

The final change to the starting XV sees Billy Vunipola picked at number eight after Ben Morgan lost his battle to recover from a knee problem.

The elevation of Vunipola and Burgess means James Haskell fills the back-row vacancy on the bench and Alex Goode is picked to provide cover at full-back and fly-half.

Lancaster will address the media at lunchtime today in his first opportunity to publicly outline the thinking behind the biggest selection call of his four-year stewardship.

Former England fly-half Toby Flood has warned that Ford's relegation to the bench through no fault of his own could leave the 22-year-old psychologically scarred, claiming he has every right to feel "pretty devastated".

There are also misgivings over Burgess' readiness to start a Test of this magnitude at inside centre, particularly given he will be facing British and Irish Lions veteran Jamie Roberts.

Burgess has spent only 10 months in union and while he has big-game experience in league, he is still learning his trade in the new code and any lapses in defensive positioning are sure to be exposed by Roberts.

England's selection has been shaped by the knowledge Wales will use a defensive system that deploys 14 players in a line with the full-back patrolling the space behind, offering little scope to circumnavigate the wall of red shirts.

The 21-16 victory in Cardiff in February was headlined by Joseph's superb try but was ultimately founded on the front-foot momentum generated by their ball carriers. The selection of Burgess and Farrell strengthens their hand in this respect.

Once the heavyweight collisions have unfolded and the match enters the decisive final quarter, reinforcements - among them Ford - are set to be summoned from the bench in the manner that proved so successful in the bonus-point victory over Fiji.

"We have a lot of respect for the Wales coaching team and their players, they are a high-quality side and I am sure it will some occasion on Saturday evening," Lancaster said.

"The support at Twickenham last week was incredible with the crowd really getting behind us and we will need them again this week to lift the players against a tough Wales team."