Fans of Palmeiras, the Brazilian club with the most national titles, have become so disenchanted with the struggling team that some players have hired security guards.
Violent threats from fan groups have increased as the team nears relegation in the Brazilian league for the second time in 10 years.
Beside players hiring bodyguards, coach Gilson Kleina has talked about the need to avoid a tragedy, and Argentina striker Hernan Barcos - the team's top star - says it won't be worth staying at the club if he starts fearing for his safety.
Even Brazil's sports minister has become involved, publicly asking for the threats to stop.
Palmeiras won this year's Brazilian Cup under coach Luiz Felipe Scolari, but now it is seven points from safety with only four rounds left.
After the team's disappointing 2-2 home draw against Botafogo last Sunday, some fans tried to invade the field and got into an altercation with police officers, injuring two of them and prompting the local football federation to ban the team's biggest fan group from matches.
The night after the game, one of the club's walls was painted with a death threat to president Arnaldo Tirone, and during the week some players said they started receiving anonymous phone calls with serious threats.
Club director Cesar Sampaio, a longtime Palmeiras idol, was told by disgruntled fans to ''watch his back.''
''We don't know if these threats are for real or not, but we are being careful,'' Sampaio said. ''We've been talking to the players to try to keep them from losing it emotionally. It's important to keep our calm in a moment like this.''
Coach Kleina, who replaced Scolari after the World Cup-winning coach wasn't able to improve the team's situation, said he fears for the players' safety.
''We have to be careful to avoid a tragedy,'' he said. ''We have to take care of these players, especially the less experienced ones.''
Barcos, who has scored 27 goals since joining the club in the beginning of the year, said he will consider leaving Brazil if he no longer feel safe.
''If it's to live like this, driving an armored car and with a gun in hand, I would rather go home,'' he said.
Sports Minister Aldo Rebelo, a Palmeiras fan, loudly condemned the threats this week.
''It's inadmissible to have threats from fans against players of any club,'' he said. ''There is no place for that in football. It's unacceptable.''
Earlier in the year, a restaurant owned by Palmeiras' vice president was badly damaged by fans after a loss to rival Corinthians. That defeat in September also prompted some supporters to partially damage a seating section at Pacaembu Stadium, which prompted the country's sports tribunal to ban the club from playing in Sao Paulo for several matches.
Palmeiras is 18th in the 20-team Brazilian league with only 33 points from 34 matches. It has lost 19 times, more than half of its matches.
Its next game is on Sunday at home against league leader Fluminense. The match can give Fluminense the title and determine Palmeiras' relegation, depending on other results. Palmeiras trails 17th-place Sport by three points and 16th-place Bahia by seven. The bottom four clubs are demoted.
Part of the team's struggles started because Scolari had the team focused on the Brazilian Cup and rested second-stringers several times in the beginning of the Brazilian league. The team's first win came only in the seventh round. But few complained at the time because Palmeiras won the Brazilian Cup, which was the team's first major triumph in more than a decade.
''I partly agree with critics who say I'm the man responsible for the team's current situation, but by the same token I have to be one of the men responsible for the team's win in the Brazilian Cup,'' said Scolari, who in 1999 led Palmeiras to the Copa Libertadores title.
Palmeiras will compete n the Copa next year thanks to the Brazilian Cup title.
The team's more radical fan groups have had a history of problems with players. In 2009, former Brazil striker Vagner Love left the club after being threatened by supporters on the streets, and this year midfielder Joao Vitor got into a fight with fans who waited for him to leave the club headquarters to criticize him.
To try to avoid further problems this year, the team has been using alternative travel routes and reinforced security during practices and matches.
Palmeiras was relegated for the first time in 2002 and easily returned to the top flight the following year.
This year's squad is led by Barcos, Chilean midfielder Jorge Valdivia - who is injured - and former Real Betis and Roma midfielder Marcos Assuncao.
The team will open its new arena in 2013, and the following year it will celebrate its centennial. Palmeiras has won eight national championships, two Brazilian Cups, a Champion Cup and the second-division title.
No other team has as many national titles, and only Santos matches Palmeiras with the eight league championships. The last time Palmeiras won the league was in 1994, with a team coached by Vanderlei Luxemburgo and led by Roberto Carlos, Zinho, Mazinho, Edilson, Edmundo and Sampaio.
''We have to keep our focus on trying to avoid relegation, we haven't been demoted yet,'' Sampaio said. ''The threats exist but there's been no violence. We need to make sure the players can be focused only on what they need to do on the field.''