Cape Town - The Blitzboks have crashed out of the Hong Kong Sevens after losing to World Rugby series leaders, the United States, 21-12 in their quarter-final encounter.

South Africa were on the board early thanks to a try in the second minute through Impi Visser with Selvyn Davids adding the conversion for a 7-0 lead.

The United States hit back through a converted try by Carlin Isles as the teams were deadlocked 7-7 at half-time.

Visser and Isles then scored shortly after half-time with Madison Hughes adding a conversion for the United States to give them a 14-12 lead.

Poor discipline at the breakdown kept the Blitzboks on the back foot for most of the second stanza and a Ben Pinkelman try, converted by Hughes, pushed the score out to 21-12 in favour of the United States.

And that's the way it ended with the United States set to play Fiji in the semi-finals of the competition and the Blitzboks to face Argentina in the 5th-place playoff at 08:55 SA time.

In other quarter-final results, Fiji beat Argentina 29-24, Samoa surprised England 14-12 and France shocked New Zealand by a similar scoreline, 14-12.