LAS VEGAS, UNITED STATES - JANUARY 24: Cecil Afrika and Branco du Preez during day 1 of the 2014 USA Sevens at Sam Boyd Stadium on January 24, 2014 in Las Vegas, United States. South Africa beat Wales 43 - 0. (Photo by Wessel Oosthuizen/Gallo Images)

Las Vegas – Reigning USA Sevens champions South Africa steamed into the Cup semi-finals on Saturday with a 36-0 demolition of Argentina in the fourth round of the IRB Sevens World Series.

Cecil Afrika, Branco du Preez, Seabelo Senatla, Chris Dry and Werner Kok all scored tries for South Africa as they smashed Argentina in their quarter-final to line up a clash on Sunday with two-time USA Sevens winners Samoa.

Samoa rallied from 10-0 down to beat Australia 12-10, with tries from Sani Niue and Lio Lolo.

Not only are South Africa eyeing a second straight US crown, they are aiming to overtake series leaders New Zealand, who top the standings with 58 points to the South Africans' 56.

New Zealand will play surprise packages Canada, who stormed back from 14-0 down to beat France 17-14 and reach their first Cup semi-final since Tokyo in 2000.

Connor Braid scored two tries before Nanyak Dala sealed the win.

“I didn't even know we'd made one before, so that's amazing. We are very excited,” Canada captain John Moonlight said of reaching the last four.

New Zealand defeated England 24-7 in their quarter-final, Waisake Naholo notching a hat-trick in the emphatic triumph.

New Zealand will be without George Tisley for their semi-final and will be missing Sam Dickson for the rest of the tournament after both received disciplinary sanctions following their final pool match against Fiji earlier Saturday.

South Africa, New Zealand, Samoa and France had all emerged unbeaten in pool play, which began on Friday and concluded on Saturday.

Second-day action also included the Bowl quarter-finals, in which Kenya defeated Spain 24-0 to advance to a clash with Scotland, 31-7 winners over Portugal.

Wales notched their first win of the week with a 12-7 victory over the United States in their Bowl quarter-final. They will meet Fiji after Ben Ryan's side defeated Uruguay 38-14.

Spain, Portugal, the United States and Uruguay will all enter the Shield semi-finals on Sunday. – Sapa-AFP