Olympic sprint champion Usain Bolt will compete in a 150 metres race on Brazil's Copacabana Beach next month against three other sprinters in what the Jamaican called a "street meet" type showdown.
Organisers are to build a track on the famous sands for the March 31 race although they did not say whether it would have a bend.
The 150 metres race is an unusual distance that rarely features in top competitions. Bolt set a world best for the event in Manchester in 2009.
A six-time Olympic gold medallist, Bolt, 26, holds the 100 metres world record of 9.58 seconds and the 200m record of 19.19, and was part of the Jamaica team that set the 4x100 record of 36.84.
The race in Rio is only the second international event Bolt has confirmed for 2013. He recently announced he will compete in the 200m at Oslo's Bislett Games Diamond League meeting on June 13. He ran a 400m recently in Jamaica.
Rio de Janeiro will host the next Olympic Games in 2016 and Bolt has said he wishes to compete here. He visited the city last October on a promotional tour.