South Africa were the only major casualty on Day One at the Hong Kong leg of the IRB Sevens World Series on Friday.

Paul Treu's Springbok team, who have never won at Sevens' showpiece event, produced another very disappointing performance to go down 0-21 to an inspired Argentinean team in the last match of the day.

With all teams playing just one match in the pool phase, Argentina and Wales topped Pool A, ahead of Australia and South Africa.

In Pool B New Zealand and Kenya both won, defeating France and the United States respectively.

In Pool C Samoa looked mighty impressive in disposing of England. Portugal lie second in the pool after their dramatic last-gasp win against Scotland

And in Pool D Fiji and Canada are in first and second place, both looking in top form against Hong Kong and Spain respectively.

We bring you all the Day One action!

Pool A

Argentina defeated South Africa 21-0 in the last game on Day One. Juan Ignacio Brex scored a try in the dying seconds to round off an impressive display by the Pumas over the Las Vegas champions - who were shockingly lethargic.

Paul Treu's side came into this tournament after an impressive victory against New Zealand in the Las Vegas final, but were unable to stop Los Pumas' captain Nicolas Bruzzone scoring two tries and now face matches with Australia and Wales on day two.

In Pool A, Wales defeated Australia 19-14, despite two tries from Lewis Holland for Michael O'Connor's side.

Results:
Wales 19-14 Australia
South Africa 0-21 Argentina

Pool B

Current Series leaders New Zealand, last year's runners-up, beat France 33-12 in Pool B, while Dennis Ombachi scored twice for Kenya to record a 17-14 victory against USA.

Results:
New Zealand 33-12 France
United States 14-17 Kenya

Pool C

In one of the most entertaining matches of the day, Duarte Moreira scored four tries for Portugal as they dramatically beat Scotland 27-21 in Pool C.

With Scotland leading 21-20 thanks to two tries from Andrew Turnbull, Moreira dotted down in the corner to secure victory, before England were undone by an impressive Samoan performance in a 28-7 defeat.

Results:
Samoa 28-7 England
Scotland 21-27 Portugal

Pool D

On an enthralling day of action defending champions Fiji proved too strong for hosts Hong Kong.

Two tries each from Ilai Tinai, Benito Masilevu and Samisoni Viriviri assisted in the 36-0 victory for the islanders, who are currently fourth in the overall standings on the World Series.

Canada, who secured their place as a core team at last year's Hong Kong Sevens, impressively beat Spain 31-7 thanks to two tries from Taylor Paris.

Results:
Canada 31-7 Spain
Fiji 36-0 Hong Kong