Toulon winger Josua Tuisova scored a try to help fire Fiji to a 21-17 victory over arch-rivals South Africa to claim the London leg of the World Rugby Seven Series.
With just the Paris leg of the Series to play, next weekend, Fiji now stand atop the standings on 167 points, with the Blitzboks in second on 160. New Zealand sit in third on 133.
"There were a lot of new boys in the squad but we performed as a team, that's why we overcame South Africa today," Fiji skipper Jerry Tuwai said.
Fiji beat Canada 40-7 in the quarter-finals before seeing off Ireland 38-12 in the semis, while South Africa edged New Zealand 14-5 in the quarters and England 29-19 in their last-four play-off.
Fiji's hopes of a fourth straight tournament win took an early blow when Sevuloni Mocenacagi was yellow carded from the kick-off for taking Justin Geduld out in the air.
South Africa immediately made their numerical advantage count, Stedman Gans scything through the stretched defence for the opening try, Geduld converting.
Fiji did well, however, to absorb the Blitzbok pressure when a man down, and showed just why they average just 23 passes per match such is the efficacity of their strike power.
Tuisova, also part of the Fiji team that won Olympic gold in Rio in 2016 but not a regular on the circuit, muscled his way past some weak defence for a try, converted by Amenoni Nasilasila, to pull the Pacific islanders level.
Paula Dranisinukula was the final recipient of an amazing display of off-loading rugby started by Semi Radradra, crossing for Fiji's second try with Nasilasila making no mistake with a conversion in front of the posts.
The Boks hit back when Ruhan Nel expertly took a high pass one-handed and rode a tackle by Dranisinukula to cross in the corner, Geduld missing the extras.
But Fiji responded perfectly, Jasa Veremalua skilfully exchanging passes with Josua Vakurunabili to go over for Fiji's third try, Nasilasila's conversion taking the Fijians out to 21-12.
Bok Zain Davids bounced through a couple of desperate tackles for a fine individual try to set up a dramatic finale, but Fiji won the restart and safely ran the ball out to seal the win.
"I found it tough today but I got help from the boys and was hanging in there. I know we trust each other and finally we get the win," said free-running Fiji back and man-of-the-final Radradra, who is quitting Top 14 club Toulon for Bordeaux-Begles next season.
Ireland, a "non-core team" in their maiden Series appearance, marked a remarkable weekend by edging England 21-19 to take third place.
Jordan Conroy scored a first-half brace of tries for the Irish, including one from 90 metres out, before Dan Bibby hit back with two of his own.
England speedster Dan Norton then took his record career try tally to 295 when he crossed early in the second half.
But Conroy showed all his gas by sprinting away for his hat-trick, Mark Roche nailing a tricky conversion to seal a memorable win.
Fiji lead the World Rugby Sevens Series standings with one leg of the competition to play