Quinton de Kock hit a blistering half-century as South Africa defeated a battling United States by 18 runs in their opening T20 World Cup second round clash on Wednesday. The Proteas piled up 194-4 off their 20 overs after being put into bat before restricting the USA to 176-6 as the Super Eights stage got underway at the Sir Vivian Richards Stadium. However, the USA, who stunned former champions Pakistan in the first round, were close to another upset when Andries Gous (80 not out) and Harmeet Singh (38) put on 91 for the sixth wicket.