The 25-year-old, a multiple world champion and 2012 Olympic gold medalist, is hoping to become the most successful athlete in the history of the Commonwealth Games.
Le Clos is six medals away from his goal. Ahead of the 2018 Commonwealth Games on Australia's Gold Coast, two shooters -- Englishman Mick Gault and Australian Philip Adams -- lead the way with 18 medals.
The pair amassed their totals over six Games. Le Clos aims to do it in just three.
In it to win it
At the 2014 Commonwealth Games, Le Clos medalled in all seven of the events he entered -- including gold in the 100m and 200m butterfly -- bringing his medal total to 12.
This year, Le Clos is chasing podium finishes in all three butterfly events -- he is a former world champion over 50m and the world record holder over 100 and 200m -- as well as a top-three finish in the 200m freestyle.
He is also hoping for two relay gold medals, though this task has been more difficult following a row over South Africa's selection policy for the Games.
Backstroke swimmer Christopher Reid and Zane Waddell, who competes in freestyle, were left out of the team after they were unable to attend mandatory South African trials in December due to study commitments in the US.
Despite this setback, Le Clos is determined.
"I just love to win," he tells CNN, "I love to compete at the highest level and I really enjoy racing."
In the race's early stages everything had been going to plan for Phelps, the most decorated Olympian of all time. But over the final 50m, Le Clos chased him down and took gold by a fingertip margin of 0.05 seconds -- ending the American's domination of the event since the 2004 Games.
Proud father
It proved the right decision. By the age of 14, Le Clos had made the senior Olympic squad, and by 18 he held two South African records. He is now his country's most-decorated Olympian.
Getting to such an elite level requires more than physical strength. As Le Clos readies himself for the start of the Commonwealth Games on April 5, there will be long hours in the pool and the gym, but also "a lot of mental, emotional and psychological preparation."
"My biggest attribute is my mind," he explains, "and my willpower to try to be the best that I can be."