Youssef competed only in the men's 100 m freestyle, as a 15-year-old, at the 2000 Summer Olympics in Sydney. He received a Universality place from FINA, without meeting an entry time. He challenged six other swimmers in heat two, including fellow 15-year-old Ragi Edde of Lebanon. He rounded out the field to last place in a personal best of 1:02.45, nearly a nine-second deficit from leader Gregory Arkhurst of Côte d'Ivoire. Youssef failed to advance into the semifinals, as he placed seventieth overall in the prelims.