A year on from what Le Clos called "the greatest moment of my life" where he denied the American great a third straight gold in his favourite event, Phelps has retired and the 21-year-old who beat him is poised to shine in Barcelona next week.
"If you asked Michael, he would have said his first gold medal in Athens was his favourite moment of all time," Le Clos told Reuters at the hilltop Montjuic complex where the swimming events are being held when the championships start on Sunday.
"So I think for me, that was going to be the best moment in my career.
"Maybe I was the happiest at that time. But I still believe I can win more gold medals in the future," added Le Clos, who has become good friends with his hero Phelps.
"If I win more gold medals I will probably be more proud of myself because I have done better but at that moment when I won the gold it was so unexpected."
After shaking off a shoulder injury sustained at the start of the year, Le Clos is a firm favourite for the 200 metres butterfly in Barcelona and he also has a good chance of a medal in the 100 metres version.
He is also competing in the 50 metres butterfly for the first time but said he would be happy just to make the final.
The experienced Takeshi Matsuda of Japan was probably the main threat in the 200 metres, with Germany's Steffen Deibler and Evgeny Korotyshkin of Russia the men to watch in the 100 metres, Le Clos said.
"I think I probably am the favourite for the 200 metres," he said.
"But for me it doesn't make any difference. I have prepared exactly the same that I would have otherwise. I just want to win the race, no matter what.
"I think I am in the best possible shape I can be considering what happened in the beginning of the year.
"If you had asked me six months ago I would have answered: well, not so good. But at the moment I am feeling strong."
Looking to the future, he said he was considering adding the freestyle to his repertory of competition events and there was no reason why he could not challenge top names like James Magnussen of Australia and American Nathan Adrian.
"Freestyle is always the hardest race to win the medals," Le Clos said.
"I want to go for freestyle because that is where all the attention is.
"It would be awesome to beat James Magnussen one day but for now it is not really the focus.
"If I can keep improving, like I have done in the butterfly, there is no reason why I can't challenge."
The men's 50 metres butterfly is on Monday, with the 200 metres on Wednesday and the 100 metres on Saturday.
- Sports & Recreation