England overcame a flat, error-strewn first half when their experimental side trailed an effervescent Japan 15-10 to turn on the power after the break and run out 35-15 winners at Twickenham on Saturday.
The long-shot outsiders had threatened a repeat of their 2015 World Cup upset over South Africa when well-made tries for Ryoto Nakamura and Michael Leitch rewarded some terrific play and a dominant 40 minutes after England had struck first through scrumhalf Danny Care.
Eddie Jones sent on most of his big-gun replacements during the second half and, inspired by Owen Farrell, they made the difference as tries for Mark Wilson, debutant winger Joe Cokanasiga and Dylan Hartley and the boot of George Ford completed the comeback.
"It was obviously very disappointing in the first half. Our attitude wasn't there, but we were much more ourselves in the second period," said Ford, captaining the side on his 50th appearance.
"Owen Farrell made a massive difference and that's what he's there for. I'm disappointed that it had to come to that, but that's why replacements are there... they swung the game our way."
England got off to a flyer with a well-made try by Care after three minutes but if the Twickenham crowd were expecting it to open the floodgates they were sorely misled. Instead Japan roared back to totally dominate the half with quick thinking and fizzing passing and they should have been more than 15-10 ahead.
They showed their intent by turning down a series of kickable penalties and got their reward when centre Nakamura swept through opposite number Alex Lozowski, who had a half to forget, to score under the posts.
England were giving away constant penalties, leading to a yellow card for hooker Jamie George, but it was not just in the area of discipline that Japan were on top. They looked quicker, sharper and more ambitious, with through-the-legs and round-the-back passes bringing gasps from the otherwise silent Twickenham crowd, who were left wondering what had happened to the team beaten by a single point by New Zealand only a week ago.
Japan got the second try they fully deserved when captain Leitch shrugged off two poor tackles, then stood up fullback Elliot Daly.
The halftime statistics told a sorry story for the hosts as Japan enjoyed 69 percent possession and 77 percent territory, conceding one penalty to England's eight.
Jones sent on Farrell for the second half, then started emptying his bench early as several of the stand-ins spectacularly failed their auditions.
It took a while but eventually the feel of the game changed as the territory, possession and penalties started to go the other way and Ford converted one of them to reduce the gap to two points after 56 minutes.
Three minutes later England were in the lead as some nice handling and a quick pass by Ford opened the way for flanker Wilson to score.
Japan had nothing more to offer and it was one-way traffic after that as Cokanasiga finished a sharp move to score and, for the second week running, Hartley was carried over by a rolling maul.
The scoreboard looked respectable in the end but there was little to celebrate for England, who complete their November programme against Australia next Saturday.
Japan, however, will take great heart from the first 50 minutes and go with some confidence to play Russia in a dry run of the opening match of the 2019 World Cup.
"We maybe lost concentration in the second half - that really cost us," said Leitch. "The key is momentum. We were a bit reluctant to get the ball into space today. We will take this loss on the chin."