The South Americans had only ever won two games at the World Cup and are ranked nine places below the more celebrated Pacific islanders, whom they had never beaten.
But they capitalised on an error-strewn performance by Fiji, whose hopes of qualifying for the knock-out stages now hang by a thread.
The thrilling game had a much deeper significance as it was played in Kamaishi, one of the towns hardest-hit by the 2011 earthquake and tsunami that devastated north-eastern Japan.
The stadium, the only purpose-built venue at the Rugby World Cup, was built on the site of a school destroyed by the waves and hosting the match was seen as a powerful sign of recovery.
As Japan’s Crown Prince Akishino looked on, the crowd observed a moment’s silence to remember the more than 1,000 people killed in the tsunami, several children in the crowd removing their caps and bowing their heads in prayer.
With emotions running high, Fiji were first on the scoresheet in the seventh minute, Mesulame Dolokoto dotting down to complete a slick line-out move that came after a delightful chip and catch by fullback Alivereti Veitokani.
But Uruguay hit back via a mazy run from scrum-half Santiago Arata, one of the smallest players on the pitch, who evaded several tackles before touching down under the posts for an easy conversion.
Fiji’s huge forward superiority eventually told as prop Eroni Mawi bundled over from close range. But Uruguay, ranked nine places below Fiji, refused to go away and again took the lead as No 8 Manuel Diana barged over for a converted try.
And the minnows leapt further ahead with 26 minutes on the clock, Juan Manuel Cat finishing off a flowing move down the left. A penalty just before half-time gave battling Uruguay a deserved 24-12 lead at the break.
Fiji had taken a shock lead of their own into the second half of their defeat by Australia, but this time they found themselves needing a dramatic comeback.
After Josh Matavesi missed a relatively simple penalty that would have steadied the nerves, lock Api Ratuniyarawa finished off a move that featured a sensational off-load.
And replacement scrum-half Nikola Matawalu dived over following an outrageous dummy to closed the gap to 22-27 and set up a nail-biting last 10 minutes.
Fiji threw everything at Uruguay, but a Felipe Berchesi penalty took them out of sight and they clung on for dear life in the final stages, Matawalu’s last-minute try not enough to prevent victory. (AFP)