Brazil striker Fred says fans swarmed his car to threaten him as he left practice, complaining about the team's recent struggles and demanding a good result.
Brazil striker Fred warns there could be "another tragedy" in Brazilian football if fan groups follow through with their threats against his club this week.
In a lengthy letter posted on his Facebook and Twitter accounts, Fred said he is concerned about what could happen to him and his teammates if Fluminense doesn't advance to the second round of the Brazilian Cup on Thursday.
He said a group of about 20 fans swarmed his car to threaten him as he left practice this weekend, complaining about the team's recent struggles and demanding a good result.
Fred, who will be a starter for Brazil at the World Cup, said he had to dangerously accelerate to escape and nearly caused an accident.
"After 'the message' this weekend, when a group of dropouts disguised as fans threatened the team's players, Brazilian football could be about to witness another foretold tragedy on Thursday if Fluminense fails to advance past Horizonte in the Brazilian Cup."
Horizonte, a minnow club without any significant tradition in Brazil, won the first leg 3-1 and is a draw away from reaching the second round.
Fluminense was also eliminated by rival Vasco da Gama in the semifinals of the Rio de Janeiro state championship last week, a defeat that prompted team officials to fire the coach.
There has been an increase in fan violence in the country hosting the World Cup in a few months, with scenes of confrontations in the stands becoming common. In the final round of the Brazilian league last year, four people were seriously injured and a decisive match was interrupted because of violence.
Fred mentioned other recent cases of fan violence in his letter, including the death of 14-year-old Bolivian Kevin Espada, who was hit in the head by a flare launched by fans of Brazilian club Corinthians. He also recalled when Corinthians fans invaded the team's training center to threaten players, and the death of a Santos fan brutally attacked by Sao Paulo supporters.
"How many more Kevins will have to lose their lives, how many training centres will have to be invaded, how many innocent people will have to be beaten to death until something serious is done against these barbarians?" Fred said. "Or will we have to wait until a player is beaten?"
The striker said it's not a coincidence there are now only empty seats at Brazilian stadiums, where "the flags that used to wave in stands have become weapons in the hands of these bandits."
Fred said he felt angry after last weekend's incident and wondered whether his dedication to the club was worth it, but later blamed just a few fans from "professional" groups who have been at the root of stadium violence in Brazil for years.
"I'll fight with the weapon that I have," he said.
"Starting today, I will not celebrate my goals near the fan groups. I'll dedicate my goals to the real Fluminense fans."