The Bliztboks secured their fourth triumph of the season as they overcame the Pacific nation 19-12 at the Sam Boyd Stadium.

The Rio 2016 Olympic bronze medallists now have a 24-point cushion in front of Fiji in the race for the overall men's Sevens Series crown.

Hosts the United States finished in third place thanks to an impressive 19-15 win against New Zealand, much to the delight of the considerable crowd inside the stadium.

"We're happy with how it's been going the last few tournaments and the guys are believing in a system and working for each other," South Africa coach Neil Powell said. 

"They are showing a lot of pride in the jersey and the fact that they can play for their country. 

"They showed a lot of composure in the final and managed to take control back in the second half."

The final between South Africa and Fiji, who were bidding for their first success of the season, proved to be a tense affair and it was the historic Olympic gold medallists who took the lead through Masivesi Dakuwaqa's try.

Blitzboks playmaker Cecil Afrika then restored parity before tries from Chris Dry and Roscko Speckman effectively killed the game as a contest.

Waisea Nacuqu hit back for Fiji but it mattered little as South Africa held on for victory.

The South African side had to battle their way through to the showpiece match in Las Vegas as they came up against a spirited American team in the semi-finals.

They were 12-10 down at half-time before a second half rally saw them fight back to win 20-17.

Fiji then joined South Africa in the final as they beat New Zealand 19-14.

Kenya took victory in the Challenge Trophy final, edging Samoa 21-14.