BRIGHTON: Japan, so often pleasing on the eye but short on stature in the face of more physical opponents, came of age as a rugby nation to stun twice winners South Africa 34-32 on Saturday, the biggest upset since the Rugby World Cup's inception in 1987.

Moulded by former Australia coach Eddie Jones into a side that matched flair and industry with ferocious tackling, Japan made all those attributes count in spectacular fashion with a last-gasp victory in their Pool B opener in Brighton.

A day after England had kicked off the six-week showpiece by quelling a fired-up Fiji at Twickenham, there were also victories for Ireland, France and Georgia.

But the day belonged to Japan, a country that will host the 2019 edition but had only one World Cup win, in 1991, to their name until now.

Nicknamed the Brave Blossoms, the men in red and white shirts finally provided a moment worthy of the moniker when they refused to settle for a probable draw when they were awarded a kickable penalty in the dying seconds of the game.

Sensing, as they had throughout that the ailing Springboks were there for the taking, Japan went for glory and after a reset scrum against a team down to 14 men and barely believing their predicament, they spread the ball wide for New Zealand-born wing Karne Hesketh to dive over in the corner.

"It's quite incredible. We thought we could compete, but to beat South Africa is a fantastic achievement for the team and it's a great day for Japanese rugby," said Jones, who acted as a consultant for South Africa when they lifted the trophy in 2007.

Fullback Ayumu Goromaru scored one of Japan's three tries and 19 points from his boot kept his side in touch despite four tries from South Africa .

For South Africa , steeped in rugby heritage and world champions in 1995 and 2007, it was a bitter blow and coach Heyneke Meyer could only apologise to the nation for his side's "unacceptable" performance.

"It was just not good enough. It was unacceptable and I take full responsibility," he lamented.

South Africa have a week to regroup before facing Samoa in Birmingham next Saturday. Japan have less time to rest, though the adrenaline will be flowing again as they aim to reproduce their heroics against Scotland on Wednesday.