Fiji survived a surging comeback to beat defending champions and World Series leaders South Africa 24-19, and advance to the Cup final at the Las Vegas Sevens.
Fiji burst out of the blocks to lead 19-0 at half-time, with the Blitz Bokke conceding a yellow card either side of half time.
The advantage was extended to 24 shortly after the break, with Semi Kunatani running in his second of the match, before South Africa sprung into life, scoring three tries in the final five minutes to come up just short.
Fiji coach Ben Ryan was relieved at the final whistle.
"If you look at the teams playing, only Japan in the core [teams] have got less tournaments [under their belt] so this is a very young side and they are making mistakes in decision making, and the only way we're going to get better is just keep playing [and] keep learning. [The] first half the game was outstanding. When we were on the money we were beautiful in that first half and South Africa are an excellent side so I'm just happy to get to the final".
New Zealand beat hosts the USA 26-12 in the second semi and form will be on Fiji's side in the final after beating the All Blacks Sevens 14-12 in pool play.
Meanwhile Samoa's struggles continued with the Manu beaten 19-5 by Kenya in the bowl semi finals, to bow out on the tournament with two wins from five games.
The USA leg is the fourth-successive tournament Samoa have failed to make the Cup quarter finals and will see them drop even lower than their current ninth placing on the World Series standings.