A bizarre second-half try helped England overcome a ragged first half and eventually overwhelm Japan 34-12 on Sunday, earning themselves a bonus-point victory and planting one foot firmly in the World Cup quarter-finals.
With the game poised at 13-12, England captain Courtney Lawes cantered in for a try as the Japanese players stopped and watched, expecting to hear the referee's whistle for a knock-on after the ball had deflected off the head of prop Joe Marler.
That turned the tide as England ran in four tries in all with Lewis Ludlam, Freddie Steward and Joe Marchant also on the scoresheet and George Ford again superb off the tee.
For the first 50 minutes though England had looked devoid of ideas, routinely kicking away possession, making way too many errors and some inexplicable decisions, and they were even booed by their own fans at one point.
They finished strongly, however, and top the Pool D standings with nine points. Japan and Samoa have five, with Argentina and Chile pointless.
England face Chile next weekend then have a two-week break before their final game against Samoa with a quarter-final against either Wales, Fiji or Australia looming.
"We are just really happy with another win tonight," said Ford. "We knew it was going to be tough and Japan challenge you in different ways. We knew it would be that third or fourth quarter we could pull away a bit.
"It was probably not the prettiest watching it. It's really hard to play with the ball in these conditions. These late kick-offs are dead greasy but we got there in the end."
Japan had won only one of their last nine games coming into the World Cup over 15 months but, buoyed by their opening win over Chile, in the first half they looked to have rediscovered much of the speed and energy that so memorably carried them to the quarter-finals four years ago.
They eventually ran out of steam, however, and the defeat ended their remarkable run of seven successive pool-stage wins.
With the Brave Blossoms 6-3 up, England finally got their first try of the tournament when they disrupted a Japan five metre lineout and Ludlum was carried over.
Ford converted but then missed for the first time in the World Cup with a long penalty, and instead Rikiya Matsuda landed his third to close the gap to 10-9.
England's travails were summed up near the end of the first half as they turned down a shot at goal to kick to the corner but then dropped the slippery ball peeling off the maul.
Lesson learned, they went for the posts with another penalty to make it 13-9 at the break.
Not much initially changed in the second half as Ford, whose three drop goals in nine minutes broke Argentina's spirit last week, never once seemed to consider the option on Sunday.
Instead it was Japan who got the first points of the half as a Matsuda penalty after 54 minutes brought them back to within a point.
England were then given their huge slice of luck as a wild pass looked to have been knocked on, only for a TMO review to show that the ball hit Will Stuart's shoulder and then Marler's head, and Lawes, who had dotted the ball down almost apologetically, was given the try.
It was all England from then on. A perfect Ford kick found fullback Steward who did superbly to get the ball down, and then some crisp passing and hard lines opened the way for Marchant to blast through for a bonus-point fourth at the death.