Michael Phelps was 15 years old when he competed in his first Olympics. He made the U.S. team for the 2000 Sydney Olympics at age 15, becoming the youngest American male swimmer to make an Olympic team in nearly seven decades. Phelps competed in the men's 200-meter butterfly and finished fifth in the final.
Although he did not win a medal in Sydney, the experience marked the beginning of an Olympic career that would span five Games. Four years later in Athens, he won six gold medals and two bronze medals. At the 2008 Beijing Olympics, he reached the defining peak of his career by winning eight golds.
The common mix-up is confusing Phelps's age at his first Olympics with his age when he first won Olympic gold. He was 19 in Athens when he became an Olympic champion. He was also 15 when he set his first world record, making his early breakthrough unusually remarkable even before his medal haul began.