Le Clos never expected to reach 100m final
Le Clos, the 200m gold medallist in his specialist stroke, qualified second fastest on Thursday for the 100m final on Friday night.
"The way we planned it was to sneak in eighth," Le Clos said.
"I never expected to make the final and be seeded second.
"It is a very big final. I'm very excited."
Regardless of whether he picked up a medal in the 200m event, Le Clos believed the South African swimmers had proved their worth, with Cameron van der Burgh having also secured gold in the men's 100m breaststroke final.
The SA swimming team did not earn a single medal at the 2008 Games in Beijing.
"Whatever happens—if I finish eighth or win a medal—I will still be proud of what I've done and proud of the team because we've done well as a unit," he said.
An overnight international swimming sensation, Le Clos cruised through his semi-final as the second fastest swimmer behind Olympic legend Michael Phelps of the United States.
Phelps and Le Clos were involved in an epic battle for the men's 200m butterfly crown on Tuesday, a tussle which Le Clos won by the narrowest of margins.
Le Clos's build-up to that magical Tuesday evening was almost identical to the lead-up to Friday night's match-up.
While the young South African would like to repeat his medal-winning feat in the 100m butterfly final, he felt it was a much greater ask to unseat Phelps over the shorter distance.
"It will be a little bit unrealistic to try and win," Le Clos said.
Meanwhile, Suzaan van Biljon, the first South African woman to make it into a final in London, finished seventh in the women's 200m breaststroke in 2:23.72 on Thursday night.
Van Biljon, who led the final after one length but faded in the second half, said Le Clos and Van der Burgh had reignited her passion for swimming.
"I thought, when I started swimming again, that 2008 was my peak, and I just bettered my time by two seconds, so it was obviously not my peak back then," Van Biljon said.
"I think it is a bright future that lies ahead. I'm really keen to see what happens in the future.
"Chad and Cameron really put back that desire into me to do something which I lost in 2008.
"Since seeing them swim, and having that gold medal, it really brought back that dream of wanting to achieve that as well."– Sapa.