On a breathless day's action at the Sam Boyd Stadium, Canada performed heroics to reach only their second-ever Cup semi-final in IRB Sevens rugby, joining defending USA Sevens champions South Africa, New Zealand and Samoa in the final four.
The South Africans, the most recent winners on the HSBC Sevens World Series, have conceded just seven points in their four matches so far at the Sam Boyd Stadium and beat Argentina 36-0 in their quarter-final with tries by Cecil Afrika, Branco du Preez, Seabelo Senatla, Chris Dry (2) and Werner Kok. They next face Samoa in an enthralling match-up between the only two sides to have won a Cup in Las Vegas.
The 2010 and 2012 champions, Samoa, came from 10-0 behind to beat Australia 12-10 with tries from Sani Niue and Lio Lolo.
In another enthralling quarter-final Canada came from 14-0 behind to reach their first Cup semi final since the Tokyo Sevens back in 2000, defeating France 17-14 with Connor Braid scoring two tries before Nanyak Dala snatched the win.
The Cannucks will face Series leaders New Zealand after the All Blacks Sevens proved too strong for England in the last of the quarter-finals, winning 24-7 spear-headed by a hat-trick from Waisake Naholo.
Gordon Tietjens' side will be without George Tilsley for one more match, however, and Sam Dickson for eight more matches after both players received disciplinary sanctions following their match with Fiji.
Kenya beat Spain 24-0 to book their place in the Bowl semi-finals and will face Scotland, who won 31-7 against Portugal with captain Colin Gregor scoring 11 points in the win and Lee Jones adding a brace of tries.
Fiji, beaten narrowly by New Zealand in the Cup quarters, are also through to the Bowl semi-finals after a 38-14 win against Uruguay. They will play Wales, who snatched a 12-7 victory against host nation USA.
Spain, Portugal, USA and Uruguay will all enter the Shield semi finals on day two.
With pool play concluded on the second of the three match days in Las Vegas, South Africa set up their quarter-final with Argentina by winning all three of their pool matches.
Having not conceded a single point on day one, Werner Kok, Stephan Dippenaar and Seabelo Senatla all scored tries in a 19-7 victory against Kenya, while Canada also qualified from Pool A after beating Wales 21-19.
Tries from Nanyak Dala, Phil Mack and Justin Douglas guaranteed Canada's win but they had a nervous wait to see if South Africa would beat Kenya to ensure their place in the final eight.
France and Argentina had both already booked their places in the quarter-finals of the Cup but it was France's 14-0 win over Los Pumas that maintained their 100% record and ensured they topped Pool D.
Dubai Sevens champions Fiji dropped down to the Bowl after they narrowly lost 12-7 to the current Series leaders New Zealand in an enthralling encounter having also lost 22-21 to Australia on day one.
The current Series leaders and Gold Coast champions, New Zealand, set up their Cup quarter versus England with their third win in Las Vegas.
Samoa also made it three wins from three in Pool C with an impressive 35-0 defeat of Portugal thanks to two tries from Levi Asifa'amatala. Dan Norton scored a hat-trick in England's defeat of Uruguay to secure their spot in the last eight.
The hosts USA recorded their first win by beating Spain 31-10 with tries by Brett Thompson (2), Folau Niua, Stephen Tomasin and Ryne Haitsuak.