Rio Slum is laying claim to having the first football pitch in the world in a modest patch of land, with floodlights generated by player movement.
The innovation, unveiled in the presence of Pele, is courtesy of a new technology called Pavegen, which can harvest energy from people's footsteps.
An AFP reporter witnessed its inauguration Wednesday at Mineira, a favela -- or slum area -- near central Rio.
Brazil great Pele said: "The whole world started looking at Brazil through football. I hope that with projects such as this one, the world will start looking at Brazil through its participation in science."
A total of 200 weatherproof tiles made from 80 percent recycled materials were installed beneath the new pitch to capture players' kinetic energy during games.
At night, that stored energy generates 100 percent of the light. During daytime, between 75 and 80 percent of the energy comes from a solar panel installed above a samba school beside the pitch.
Pedro Paulo Ferreira, chairman of the local residents' association, was impressed.
"We are starting to believe more in the help of private firms than the state, which has proposed so many projects here without ever actually doing anything," he said.
Although the project has brought light, it is not all sweetness.
Players say each team has to pay 50 reais ($20) an hour to play -- 70 at weekends -- a small fortune for people living in the slum.
Residents had approved the scheme in a public vote but there are now doubts.
"From Monday to Friday the pitch is empty," said Bruno Olivera, a 25-year-old hospital worker.
"Today, we have to play outside our community as we can't pay. People who do play here have come from elsewhere."
Pavegen's chairman and founder Lawrence Kembell-Cook acknowledged the problem.
"We are still developing this technology in such a way as to bring down the cost," he told AFP.