Belgian judoka Dirk Van Tichelt ended up in the hospital not too long after winning a bronze medal.
After finishing third in the 73-kilogram judo competition on Monday, Tichelt spent the night celebrating his accomplishments at Copacabana Beach.
Tichelt set off in pursuit of a thief who stole his training partner's mobile phone and was attacked.
"While chasing this person, an individual hit Dirk van Tichelt in the face," the Belgian Olympic Committee said in a statement reported by Europe Online Magazine. "The police, which was near the location of the incident, intervened."
They found that the Brazilian individual was the aggressor and van Tichelt was "the victim," the committee said. The Belgian athlete was taken to hospital, but did not require medical treatment.
Although he did not need any additional medical attention, van Tichelt left the incident with a black eye.