Ahead of the 2014 World Cup, the Brazilian government's push to regain control of suburbs known as favelas from drug gangs has sought the help of an unexpected source - a martial arts expert from Oldham, Greater Manchester.
Grand Master Kevin Lloyd is used to teaching people self-defence at his gym but has now passed on his skills to some of the toughest police forces in South America.
The 58-year-old Muay Thai instructor recently held sessions with the BOPE, a special forces unit of the Military Police in Rio De Janeiro.
Mr Lloyd said his approach was not to teach someone how to "beat somebody up" but was about "self-preservation".
Many residents and police officers have died in clashes in Brazil since efforts to "pacify" favelas began.
The BOPE, one of the groups tasked with carrying out this push, is based in the mountains above the city in a heavily-guarded base.
"Driving up the road to the base we were stopped at the gates," Mr Lloyd said.
A sign bearing the skull logo of the BOPE greets visitors with the warning: "No sudden movements".
'Disciplined and loyal'
Mr Lloyd held several sessions with officers in the base's gym.
He was visiting Brazil in his role as secretary general of the World Muay Thai Federation when he received an unexpected offer to teach the BOPE.
He said: "They do other types of martial arts, but they were trying to broaden their knowledge further.
"The individuals are quite disciplined and are very loyal to each other. They have a good standard of fitness and health and mentally they are very alert as well."
His work usually consists of running Oldham's Siam Camp gym.
Grand Master Lloyd said Muay Thai was an effective form of self-defence.
"It's about knowing how to handle a certain situation," he said. "Martial arts are learnt and then only used if and when needed. It's to help the [Brazilian] forces to adapt and provide a bit of safety for them."
Several anti-World Cup protests have been staged in Brazil recently due to the cost of hosting the event.
Many argue the money would be better spent on health, education and social housing.
Grand Master Lloyd said the inequality seen in Rio was striking.
He said: "You can go from one side of town to the other side and you can see two different levels of how people live."
The first episode of Welcome to Rio, which features the BOPE, is available to watch on BBC iPlayer. The second episode is broadcast on Tuesday 3 June at 21:00 BST.