Chile's Nicolás Massú defeated the United States' Mardy Fish in the final, 6–3, 3–6, 2–6, 6–3, 6–4 to win the gold medal in Men's Singles tennis at the 2004 Summer Olympics. In the bronze-medal match, Chile's Fernando González defeated the United States' Taylor Dent, 6–4, 2–6, 16–14. Massú became the only man to win both the singles and men's doubles gold medals at the same Olympic Games. The two medals were Chile's first in men's singles, and Massú's gold plus the Chileans' doubles gold remain the only two gold medals for Chile at the Olympics.

Nicolás Alejandro Massú Fried, nicknamed El Vampiro, is a Chilean former professional tennis player and a coach. A former world No. 9 in singles, he won the singles and doubles gold medals at the 2004 Athens Olympics. He is the only man to have won both gold medals at the same Games since the re-introduction of Olympic tennis in 1988, and they are Chile's only two Olympic gold medals. Massú also reached the final of the 2003 Madrid Masters and won six singles titles. He was the coach of 2020 US Open champion and former world No. 3 Dominic Thiem from 2019 to 2023.