Britain's Shanaze Reade won the second round of the
BMX Supercross World Cup
in Argentina to cement her position on top of the series leaders' table.
Reade, who also won Friday's time trial super final, was put under pressure by Olympic champion Mariana Pajon.
However, she managed to stay in front and win by half a wheel to repeat last month's success at the Manchester leg.
"I am so tired and in the same time so happy," said Reade, who
finished sixth in the London 2012 Olympic final.
"To have the Olympic Champion on your back in the final and then win it makes it even more special.
"This year I want to win the overall BMX Supercross World Cup series and win the World Championships."
Colombian Pajon made her move on the final bend and was side-by-side with Reade down the final straight but the British rider edged it on the line, with Laura Smulders of the Netherlands taking the bronze medal.
America's Connor Fields won the men's race after also winning the time trial.
The third leg of the series is held in the Netherlands from 15-16 June, with the fourth and final event taking place in America from 27-28 September.
The 2013 BMX World Championships will take place in Auckland, New Zealand from 24-28 July.