Owen Farrell has been selected at stand-off, with George Ford demoted, Sam Burgess at inside centre and Billy Vunipola at No 8 in place of Ben Morgan, who has a knee injury.
Brad Barritt has been shifted to outside centre after a chest injury for Jonathan Joseph and to accommodate Burgess, who has 112 minutes of Test experience, in Lancaster’s 14th centre combination.
“There is definitely no panic,” Lancaster said. “I am backing our own players. I’m backing the players we’ve picked for the matchday 23.
“Don’t assume because we’ve picked the backline we have that all we’re going to do is play route one. I’d be disappointed if we’ve spent all this time over the last 12, 18 months, developing our attacking game to just suddenly tuck it up our jumpers and just try to smash our way over the defensive line.
“There’s got to be some subtlety in there because Wales are too good defensively to break down that way.
“We’ve got thoughts about how we’re going to utilise the tools that we’ve got. It’s not for now, because otherwise I might as well tell [Wales head coach] Warren Gatland the whole game plan.”
While Burgess’ selection ten months after his conversion from rugby league is the subject of much conjecture, so too is the decision to revert to Farrell having had Ford as first-choice stand-off since last autumn. Lancaster anticipates having a No 10 debate for some time to come.
“Owen wasn’t available in the Six Nations. George was fantastic,” Lancaster added. “We’ve got two players who are going to be world class, if not world class already, in that position. We’ve got this situation now for the next five or six years.
“Since that Premiership final, where Owen was man of the match, he’s been pushing hard. He contributed well last week against Fiji. He’s pushed George hard and I think it’s the right time to start him, in a big game like this.”
The Farrell/Burgess/Barritt combination – the most muscular trio available to Lancaster – has been chosen in anticipation of the looming gainline war with Wales.
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. It is his second start.
“It’s a big game for him,” Lancaster said. “I don’t think it’s a gamble. People said at the start it was a gamble to put him into the 31-man squad. Day by day, week by week, he’s begun to prove people wrong.
“He has more than proven in the last three months he is capable of playing at this level. He’s not got the international rugby union experience, but he’s got the big game experience.”
“I’m 100 per cent certain he’s ready for it,” Lancaster added. “My confidence has grown on the back of what he’s done, the way he’s come on and contributed off the bench.”
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 stand-off.
It is a potentially pivotal clash in the pool, which also includes Australia, but Lancaster insists the World Cup is about more than tomorrow’s game.
“It means a lot to the Welsh, but equally to the English as well,” he said. “You then layer on the fact it is a Rugby World Cup and the pool we are in, but equally it is important to state that it is not the end of the World Cup, this game on Saturday. There’s still more games to come in this pool, there’s still a lot more to be decided, but all roads do lead to Saturday.”