Argentina coach Daniel Hourcade feels his side's ability to take their chances paved the way to victory over South Africa in Durban on Saturday.
Los Pumas' 37-25 triumph in Durban was their first ever win over the Springboks and follows two narrow defeats to the Springboks during last year's Rugby Championship.
"We seized the opportunities that were presented and that was a big difference," said Hourcade.
"Previously we have not been able to do that."
Hourcade believes the result is a shot in the arm for his team ahead of the Rugby World Cup in England which kicks off on September 18.
"It gives us self-belief and makes us more confident to continue what we are doing," he added.
"I'm very happy because we played a perfect game. We were organised, defended well and were effective in attack, which allowed us to score four tries."
Hourcade hailed his side's effort and feels they they were deserved winners as they dominated in every facet of play.
"We were better in all aspects of the game for the full 80 minutes," he said.
"We improved a lot in the scrum from previous matches and in our attack – and that allowed us to beat one of the major powers in world rugby.
"It means we finished the Rugby Championship in the best possible way by achieving an historic result to give us a lot of confidence ahead of the World Cup.
"We played well and we won the mental battle. That is the key to beating the Springboks, you need to be mentally tough."