Billed as Brazil's first player-powered football pitch, a field in a Rio de Janeiro slum harnesses the kinetic energy of players' movements to provide night-time illumination.
Football legend Pele was on hand for the pomp-filled event in the Morro da Mineira slum, which saw a local youth team put the system to the test.
Under the project, sponsored by Royal Dutch Shell, about 200 energy-capturing tiles developed by British startup Pavegen were installed the width and breadth of the field and covered by a layer of AstroTurf.
Working in conjunction with solar panels also installed around the field, the player-powered tiles feed electricity to a system of floodlights overhead.
While the head of Pavegen, engineer Laurence Kemball-Cook, took pains not to reveal the exact science behind the tiles, his father and the company's chairman, Richard Kemball-Cook, said they use a system of cogs. When stepped on, the cogs spin like tops and act like generators, he said.
Each tile now costs about 500 US dollars (£310), but the price is falling as the 35-employee company refines its manufacturing process, Mr Kemball-Cook said.
Pavegen has installed similar tiles in train stations in Europe, shopping centres in Australia and Terminal 3 of London's Heathrow Airport, Laurence Kemball-Cook said, but the football field is a first.
"We've effectively turned this community into a real-life science experiment," he said. "I believe this technology can be one of the future ways we illuminate our cities."
Pele got emotional over the project, tearing up as he said he hoped the new field would help spark local kids' interest not only in football but in science.
"My father named me Edson after Thomas Edison," said the longtime star striker, whose birth name is Edson Arantes do Nascimento.
He said he hopes the next generation of Brazilians will help bring the country as much success in science as it has had in football.
"I'm sure that soon the number one scientists in the world are going to be Brazilians," Pele said as he brushed aside a tear.