Jamie George vowed that a "very different" England would take to the pitch for the World Cup quarterfinal against Fiji on Sunday than the one that edged Samoa in their final pool match.
Despite their unimpressive pre-tournament form, England topped their pool after convincing victories over Argentina, Japan and Chile, before wrapping up the group stage with a turgid one-point win over the Samoans.
"Last weekend wasn't good enough, it was poor. We've had a really good, open review," Saracens hooker George said Wednesday of the 18-17 victory last weekend.
"Our energy levels were poor. That's probably inexcusable, to be honest. Would we rather it then than now? Yes. Are we going to learn from it? Absolutely.
"You'll see a very different England team on Sunday," against Fiji, who beat the English for the first time in both sides' final World Cup warm-up match at Twickenham.
George insisted the England squad, all of whom trained with no injury issues on Wednesday, were totally focused on taking on the Fijians.
"The quarterfinal of a World Cup is exactly where we want to be, and next week we want to be in the semifinal and so on," he said.
"We can't shy away from the fact this is one of the biggest games we're ever going to play."
England scrum coach Tom Harrison highlighted the improvements Fiji had made at set piece of scrums and line-outs.
They have transformed themselves from a team previously better known for off-loading strike runners in the backs as their sole attacking option.
"Last weekend we had some good challenges," Harrison said.
"We put on a good performance in the scrum, but weren't probably rewarded as we felt we could have been, but we provided some quality ball to play off.
"Fiji will be another challenge with the strength they've got in their front row... all those players playing in top leagues in different countries will pose us a different challenge, but we'll be well prepared for that."
The Pacific Islanders, coached by hard-nosed former international Fiji lock Simon Raiwalui, had cut down on infringements around the set piece, Harrison said.
"They've managed to reduce the amount of penalties they give away. They're big human beings who will rely on that and try and overpower you there, so we have some strategies in place to deal with that."
Come Sunday, George will be packing down in the front row against a Saracens teammate in the shape of prop Eroni Mawi.
"Fiji's set piece as a whole has got a lot better," George said.
"Eroni is a very, very strong man. He came to Sarries as quite a raw but very talented rugby player.
"Eroni showed he's a very talented scrummager, very strong, and he'll pose a big threat this weekend, but I guess inside knowledge is always good when it comes to scrum time!"