Angry protesters have clashed with police in a busy tourist area over the death of over a 26-year-old man - his friends claim police mistook him for a drug dealer.
Unrest in Rio has worsened after several police-related deaths in the last week and with the England squad using the city as their World Cup base, security here will be a concern for travelling supporters.
Brazil-based journalist Tim Vickery has warned England fans to be on their guard at the tournament - especially away from the areas popular with tourists.
"Lots of England fans will be staying in the Copacabana area," he told Sky Sports News. "During the World Cup there will be a massive security operation in the area - to protect the five-star hotels.
"I fear that the resources of the security services are really going to be stretched."
Elsewhere, FIFA's top World Cup official has turned up the heat on Brazil after visiting Sao Paulo's Itaquerao stadium.
Secretary General Jerome Valcke admitted there was "not a minute" to waste to get the venue ready for the opening match between the hosts and Croatia on June 12.
Valcke, part of a delegation that included Brazil star Ronaldo, said local organisers were "running against time" but insisted they knew there was "no choice" but to meet deadlines.
"There is not a single minute we can waste, because there is still a lot of work to do," Valcke said.
"We are running against time, but yes, the stadium will host the opening game and, yes, we will organise the opening game and all the other games in this stadium.
"I can tell you that it will be a very tight schedule over the next weeks in order to be ready for the opening game, and more important, to be ready on time for us to test the stadium."
Only one FIFA test event has been scheduled for the Itaquerao venue before it officially opens - a Brazilian league match in mid-May - but that will take place without a full 70,000 crowd.
Valcke also admitted to concerns about two other stadiums - the Arena da Baixada in Curitiba and the Arena Pantanal in the wetlands city of Cuiaba.
Curitiba's stadium is due to host four first-round fixtures - including Spain's match against Australia - but 27,000 seats are still to be installed, with 5,000 still missing in Cuiaba.
FIFA wanted all 12 World Cup stadiums finished at the end of last year, but only the six used in the Confederations Cup were ready.