Twickenham - Eddie Jones said his team "played like England" in the second half after they came from behind to beat Japan 35-15 at Twickenham on Saturday.
England, showing 11 changes to the side that suffered an agonising 16-15 loss at home to world champions New Zealand last week, opened the scoring with a third-minute try from scrumhalf Danny Care.
But they were outplayed for much of the first half, with Japan deservedly leading 15-10 at the interval thanks to tries from centre Ryoto Nakamura and captain Michael Leitch.
At that stage Japan, the hosts of next year's World Cup, were threatening an upset to rival their stunning 34-32 defeat of South Africa at the 2015 edition in England -- a victory achieved when Jones was their coach.
But England regained control in a second half where they scored tries through openside flanker Mark Wilson, debutant wing Joe Cokanasiga and replacement hooker Dylan Hartley.
"Maybe we got seduced after scoring an easy try in the first few minutes," said England coach Jones, referring to Care's score.
"The players subconsciously think it's going to be easy and that showed in our attitude and effort, which was disappointing."
"Japan are a difficult side to play against if you haven't played them before but I think our second-half response was excellent," added Jones, whose side complete their November programme at home to his native Australia, fresh from a 26-7 win over Italy in Padua on Saturday.
Former Wallaby boss Jones added: "It was a game that tested us today -- we put out a different team, different combinations and was a fantastic test for us and our players will have learnt a lot from it.
"The attitude was better and we played like England in the second half."
Asked if he had given his side the kind of stern 'hairdryer' half-team talk beloved of former Manchester United football manager Alex Ferguson at the interval, Jones joking replied: "It's different these days. Once you get past 55 you tone it down!
"We just talked about the fact we needed more effort and needed to get stuck in. We weren't getting stuck but started doing that in the second half."
Saturday's match was just the second full Test Japan had played against England, who thrashed the Brave Blossoms 60-7 at the inaugural 1987 World Cup.
But Jones was delighted to see a Japan side, who are still among rugby union's tier-two nations, challenging one of the sport's major powers.
"When I brought them over to Europe we played Georgia, Romania and the French Barbarians," he said. "But now they get to play the All Blacks and England in front of 82,000 at Twickenham.
"It's fantastic for them. They are a proper rugby country and I'm really pleased for them."
Jamie Joseph, the current Japan coach, said the match had been a valuable learning experience for his side ahead of the World Cup.
"There was a lot of belief in our camp, although 80,000-odd people at Twickenham didn't believe it," he said.
"I'm very proud of how our players matched England physically most of the time," the former New Zealand and Japan back-row forward added.
"When it comes down to the crunch we were sloppy in the second half and conceded a couple of soft tries.
"That was disappointing but a good lesson for us heading towards the World Cup."