KINGSHOLM, Gloucester -- After the heroics of Saturday's victory over South Africa, a clash four days later with Scotland proved too arduous a task for a tired Japan side.

The Brave Blossoms stunned the sporting world by defeating the two-time World Cup winners in the Pool B opener. Fast forward four days and, while none of the bravery had been lost, the vibrant energy that brought an 80th-minute try against South Africa was slowly replaced with fatigue.

Japan took their win in Brighton to the wire, but in Gloucester they shipped 33 points in the second half. The loss of key man Amanaki Mafi, who was taken to hospital with what looked like a serious knee injury, seemed to spark the rout with Scotland running in five tries in total, all of them after Mafi's departure.

Magnanimously, Japan head coach Eddie Jones refused to use tiredness as an excuse in his post-match analysis, but admitted the four-day turnaround was far from ideal when trying to prepare for Test match rugby.

"I said we weren't going to use fatigue as an excuse, and we're not," Jones said. "Scotland were too good for us, they played too good in the second half. They scored 33 points in the second half to our zero [after a 45th-minute penalty by Ayumu Goromaru closed the scoreline to 12-10].

"Of course [the turnaround] is difficult. You look at anything involved in any sort of physiology, you need a six-day turnaround. That's not the case here, so you've got to suck it up and do the best you can. We play a high energy game, so the boys need a good break now."

Amanaki Mafi was carried from the field on a stretcher © Getty Images

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While Japan had spent Saturday laying everything on the line, Scotland had their feet up. Wednesday was their first game of the tournament. They took time to get started, with just the boot of Greig Laidlaw to trouble the scoreboard in the first half. Japan even posted the opening try, via Mafi, and had Scotland under considerable pressure as the first 40 drew to a close.

The second half, however, was a different story. In Mafi's absence, Scotland's energetic midfield began to run riot through a disorganised Japanese defence. Stuart Hogg jinked past tacklers at will, while Finn Russell - on his 23rd birthday - was thriving off quick Laidlaw ball. The scrum, in which Japan had used urgency to nullify the Springboks last weekend, was all Scotland, and a bonus-point victory was no more than the boys in blue deserved.

"We had our chances," Japan lock Justin Ives told ESPN. "If we'd converted early in the second half, we might have been able to pick each other up a bit more, but that last 30 minutes was tough for the guys who played on Sunday.

"We've just played the greatest game of rugby in history, so having to try and bring it all back four days later is a pretty tough ask. But it's a World Cup. If you'd said to us six months ago we'd have won one and lost one in the first two games, it's still a dream come true."

In fairness to the fixture list, Japan now enjoy a 10-day rest until their next match, against the dangerous Samoa. But the fact they played the pool's two biggest beasts within four days of each other seems a particularly harsh quirk of scheduling. The brutal nature of Test rugby saw them change six for Wednesday's fixture, and wing Male Sa'u admitted players had been working hard to regain their focus.

"Your mind was still on that history, but we had to focus on Scotland with a short turnaround," he said. "We went in with the same gameplan and mentality, but it just happened for Scotland. They played too well.

"It was a case of each individual preparing mentally. We knew it was going to be a hard game and it was Scotland's first match. We said in the camp that physically and mentally we had to show up. We did for the first 60 minutes but then it just slipped away."

Even the most hard-headed of World Cup fans will admit the pool stage can often be a procession of the Tier 1 nations to the quarter-finals. Japan, however, have changed that perception. South Africa will still expect to qualify for the last eight, and Scotland could well join them, but the story of the tournament so far is Japan.

Gloucester fans, whose Cherry and Whites play in similar colours to the Brave Blossoms, were out in force to support the supposed underdogs. Speaking to two such supporters who spoke to ESPN said they were taken by Japan's enthusiasm for the game and determination to play attractive rugby. Such adoration was not lost on prop Keita Inagaki, who admitted the comedown from Saturday's high had been a sudden one.

"This has been a new experience for me," he told ESPN via a translator. "Walking on the street, sitting on the bus, we had the local people waving and cheering for us. We were really happy to see that.

"That makes me even more disappointed for today's loss, because of how happy I was about the reaction from people after we beat South Africa. We can't take this game back, so we need to switch onto the next game. We've got 10 days so we have to work hard for Samoa."