"After winning the 200m, people were saying that the time was not fast. So I just wanted to prove to everyone that I could win the 100 and do a fast time," Le Clos said.
Le Clos, who had earlier in the competition won the 200m butterfly, was only fifth at the turn, but won in a time of 51.06, beating Hungarian Laszlo Cszeh by 0.39 seconds.
Poland's Konrad Czerniak won the bronze In winning his second and South Africa's fifth medal in the Palau Sant Jrodi in Barcelona, the 21-year-old broke his own South African record, which stood at 51.44.
Le Clos, who famously beat American superstar Michael Phelps in the 200m butterfly Olympic final last year and also won silver in the 100m, admitted that he had been nervous before the race.
"I was so worried last night, I did not get a lot of sleep in and I was really nervous this morning," he said.
"But when I woke up half past three in the afternoon, I felt much more relaxed. The closer I got to the race, the more relaxed and confident I became and I thought that I really had a good chance of winning it."
Le Clos said he was very happy that big names like Ryan Lochte were competing in the race. "The bigger the names, the bigger the hype is and it is good for the sport," he said.
"Once the race starts, it makes no difference who is racing against me, I just want to win."
He said winning the 100m felt different than winning the 200m. "This one is very special," said Le Clos.
"Ryan Lochte came in and he really wanted to win. That gave the race extra flavour, I think it was one of the biggest races of the night.
"The crowd just would not keep quiet and I went: 'Chad, don't jump into the pool,' and then I was getting nervous and I thought that it was time to get going."
He said that when he came out, he still felt strong. "I am not even tired now, I feel like going again." – Sapa