Argentina, who scored two second half tries to beat England 19-14 in San Diego last year and claim only their second IRB Sevens World Series title, will also face Japan in Pool D.
Series leaders New Zealand - winners of the opening two legs in Dubai and George in December - are the top seeds for the fourth leg of the 2009/10 Series and will face Australia, France and Guyana in Pool A.
Fiji currently lie second in the Series, 12 points adrift of New Zealand after reaching the George final and top Pool B. They will face hosts USA, Canada and South Africa, the 2008/09 Series champions they beat in the Cup quarter finals in both Dubai and George.
Dubai runners up Samoa head Pool C and will face George semi finalists Kenya, Scotland and Chile on day one at the Sam Boyd Stadium as they seek to win a first Series title since London in 2008.
The move to Las Vegas comes at a time when Rugby Sevens is enjoying unprecedented popularity and interest around the globe, while the success of the USA team has reached out to new fans across the United States.
Last year's USA Sevens attracted a crowd of 38,750 and was broadcast on US network television for the first time with an audience of 1.4 million and the 2010 event in its impressive new home promises to set new standards.
"It is exciting to be holding the fourth leg of this year's Series in Las Vegas for the first time. I am sure that the teams and travelling supporters will be treated to a warm welcome, a festival atmosphere and what promises to be the best USA Sevens to date," said IRB Chairman Bernard Lapasset.
IRB Sevens Manager Beth Coalter added: "I have no doubt that this will be a special event and the fans can look forward to mouth-watering matches on day one, including a repeat of last year's USA Sevens final, another meeting between Fiji and South Africa and hosts USA facing Canada again."
"We also welcome Chile, Japan and Series newcomers Guyana alongside the core teams, highlighting the universal spread of Rugby Sevens and I am sure there will be plenty of excitement at the Sam Boyd Stadium to keep the fans on the edge of their seats all weekend."
Ray Peterson, Managing Director USA Sevens LLC, added: "World class athletic competition and a first class Rugby experience are the cornerstones of the USA Sevens. This schedule underscores the growing global appeal to be found at this event."
Rossi Ralenkotter, President/CEO of the Las Vegas Convention and Visitors Authority, added: "As a destination renowned for world-class hotels, dining and entertainment, Las Vegas is proud to host a world-class sporting event with the USA Sevens Tournament. It provides a platform to showcase Las Vegas as a great sports destination to domestic and international audiences."