At the 2004 Summer Olympics in Athens, Papachrysanthou qualified for the men's 50 m freestyle by eclipsing a FINA B-standard entry time of 23.04. He challenged seven other swimmers on the sixth heat, including three-time Olympian Julio Santos of Ecuador. He edged out Thailand's Arwut Chinnapasaen to take a fifth spot by a hundredth of a second (0.01), outside his entry time of 23.51. Papachrysanthou failed to advance into the semifinals, as he placed forty-fifth out of 86 swimmers in the preliminaries.