Racing Club midfielder Giovanni Moreno turned up for practice flanked by police and accompanied by the president of the players union on Wednesday.
Moreno was threatened at gunpoint on Tuesday by hooligans – known in Argentina as "barrasbravas." They stuck a pistol into his knee and promised to "blow off" his leg unless he played better for struggling first-division team, regarded as one of the "big five" in the local game.
"We think no one should have to go through something like this," Racing Club president Gaston Cogorno told reporters Wednesday. "Racing will investigate this completely until we get to the bottom of it."
Fan-related violence is endemic in Argentine football. It has escalated in recent weeks with threats against players and heads of several clubs.
The vice-president of Independiente — another of Argentina's most important clubs — received death threats attributed to a hooligan gang with connections to the club. He resigned earlier in the week, and then recanted and said he was taking a 30-day break away from club business.
Moreno has not spoken publicly of the incident.
"He's worried about his family," his agent Agustin Jimenez said. "His wife is afraid. These are things that go on in the country where we live."
Racing Club lost 2-0 on Sunday to Boca Juniors and is near the bottom of the standings.
"When your two children are crying and ask you to leave it all, this does make one want to continue and be a martyr for the club," Jimenez said.
Independiente club president Javier Cantero has in past weeks aggressively tried to bring the club's hooligans under control. He has complained of receiving little support from other clubs, singling out Boca Juniors — one of Argentina's best known clubs — by name.
The sports newspaper Ole reported Wednesday that Daniel Mancussi, a board member of famous Buenos Aires club River Plate, received a threatening text message that said: "Promotion or death."
River was demoted last season to the second division, setting off riots in part of the Argentine capital. The club has been struggling this season to return to the first division.
"If another board member has received threats, I don't know," said Daniel Passarella, the River Plate's president.
Passarella was the captain of the national team in 1978 when Argentina won the World Cup. He also coached Argentina in the 1998 World Cup.
River Plate has won 33 league titles, which is more than any another club.
At least six people have died in the last six months in football-related violence, according to non-profit group Let's Save Football. The group has criticized the Argentine Football Association, alleging that it has done little to stop violence.
Almost every major club in Argentina has ties with hooligan gangs, which are granted favours in exchange for supporting clubs' directors and often their political and labour connections. The gang members park cars, sell tickets and are widely reported to be involved in selling drugs.
They also have a history of intimidating players and reports have suggested that threats are often issued with the consent of the clubs' management.