The men in green are the side to beat in this year's series and Sunday's triumph means they now command a 24-point lead atop the overall standings, adding to wins in Wellington, Sydney and Dubai.
"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," said head coach Neil Powell.
After conceding an early try against Fiji in Sunday's closely fought final, Powell's side rallied to win 19-12 with tries from player of the tournament Rosco Specman, Cecil Afrika and Chris Dry.
"They are showing a lot of pride in the jersey and the fact that they can play for their country," Powell added. "They showed a lot of composure in the final and managed to take back control in the second half."
'Lucky number 11'
Specman, who scored five tries and made as many clean breaks in Vegas, said he felt he had big shoes to fill as the replacement for Seabelo Senatla
. The legendary speedster recently switched to 15-aside rugby after setting the series alight as the top try scorer.
"I think maybe it's lucky number 11," said Specman
. "I am wearing the shirt from Seabelo, maybe it is giving me that little bit of extra speed!"
If the 27-year-old was gifted with an extra yard of pace then it was certainly put to use in the final as he showed a clean pair of heels to tear away from the Fijian defense and score his side's third try.
Yet the Vegas event was by no means a walk in the park for the Blitzboks. The path to the final involved narrow victories over home favorites USA (20-17) -- who eventually finished third -- in the semifinals, and Australia (17-14) in the quarters.
With 107 points at the midpoint of the World Series, the Blitzboks are on course to win their first ever championship title.
Reaching the final means Fiji leapfrogs England into second place, but the Olympic champion -- yet to win a tournament this season -- still has a way to go before bridging the healthy gap held by South Africa.
In the women's series, New Zealand emerged convincing winner in the final, beating Olympic champion Australia 28-5. Recording a second victory in three tournaments, the Black Ferns went six points clear of their rivals in the standings.
The men's series resumes in Vancouver next weekend, while the women's sides will next be seen in action when the series visits Kitakyushu, Japan, in April.