Hayden's first Olympics were the 2004 Summer Olympics in Athens, as part of the Canadian swimming team. At the time Swimming Canada had been in a steady decline and wound up with no medals in Athens. It was a disappointing first Olympic appearance for Hayden, as inexperience took its toll on the 20-year-old. His best individual finish at the Games was thirteenth in the 200-metre freestyle event. It was further worsened when Hayden was mistaken for a protester and beaten up and arrested by the riot police because he was "tall and wearing a dark shirt" the night before the Closing Ceremonies, a week after his competition ended. The injuries sustained left him unable to compete at the World Short Course Championships which were being held a month later.