Head coach Lancaster has restored fit-again Jonathan Joseph to the centres at the expense of Sam Burgess, who drops to the bench, for the pivotal Pool A contest at Twickenham.
Lancaster conceded England must win to avoid the earliest exit of any World Cup hosts in history, before shouldering extra pressure on his own future. When asked if his entire time with England hangs on this week after the 28-25 defeat to Wales, Lancaster said: “I think that’s fair to say.
“It’s a must-win game because if we lose we don’t get out of the group. So there’s no point hiding where the accountability lies.
“As a head coach you don’t take the players beyond Saturday, you take them to Saturday. You put them in the right place to play a strong game on Saturday.
“There’s no denying it, the stakes are huge for us, but the boys will be ready.
“I’m not going beyond this game, there are a lot of things to play out over the next two weeks.
“You can’t spend your time thinking about what’s happened in the past or what might happen in the future. If you distract yourself with the what-ifs then you aren’t doing your job.
“It was a big blow to lose Jonathan Joseph last week, he’s hard to replace. To have him back in the team is a real positive. I still had my fingers crossed in the fitness test yesterday, but he’s ready to play.”
Bath centre Joseph has recovered from the pectoral muscle problem which kept him out of last weekend’s crushing loss to Wales just in time to resume his midfield partnership with Brad Barritt. Saracens hardman Barritt steps back into the 12 shirt, after criticism for his errant showing at outside centre against Wales.
Owen Farrell starts again at stand-off, with Ben Morgan slotting in at No 8 with Billy Vunipola out of the competition with knee trouble. Joe Launchbury partners Geoff Parling at lock, with scrum-half Ben Youngs fit to continue after an ankle knock.
Nick Easter is on the bench in favour of James Haskell, with George Kruis covering lock from the replacements for England.
Former Australia coach Bob Dwyer has claimed Joe Marler cuts illegal angles at the scrum, but Lancaster refused to dignify those remarks.
“We don’t get a chance to speak to referees before World Cup games but we’re in constant dialogue with [referees’ manager] Joel Jutge,” said Lancaster.
“Certainly over the last couple of years we’ve had very good feedback from him, consistently.
“I think our scrum has been good, honest and excellent across the last three years.
“We’ve also got a high-quality referee in Romain Poite and he’s more than capable of refereeing this game without anyone’s help, I’m sure.”
Australia boss Michael Cheika accepts England believe the Wallabies have a “weak” forward pack – but Lancaster denied that was the general perception among his squad.
“No, I don’t,” said Lancaster, when asked if he thinks Australia have an underpowered pack.
“They’ve improved but I think we can put pressure on them. They’ve got two very, very good breakdown experts.”