MOSCOW -- A masked man threw acid in the face of Sergei Filin, the artistic director of the legendary Bolshoi Ballet, on Thursday night, leaving him with third-degree burns and possibly threatening his eyesight, Bolshoi officials said on Friday morning.
The attack followed a series of anonymous threats to Mr. Filin, 42, a dancer who rose through the ranks of the world's largest ballet company to become its head.
Investigators have not ruled out a dispute over money or property, but are focusing on the theory that Mr. Filin was targeted because of his work, a police spokesman told the Interfax news service.
As dancers kept an overnight vigil at the burn unit where he is being treated, his colleagues said they suspected that professional jealousy was behind the attack. In recent weeks, his tires were punctured and his car scratched, and his cellphones and personal e-mail account were hacked and correspondence published, his associates have said. A relative had offered to supply Mr. Filin with a bodyguard, but Mr. Filin refused because he did not believe that the threats would lead to physical violence, said Dilyara Timergazina, his assistant and adviser.
The threats, she said, "don't show that someone with great conceptual thinking is behind that, but someone very primitive, with unhealthy aspirations -- I don't know how to put it -- someone full of hate."
Katerina Novikova, the Bolshoi's spokeswoman, said Mr. Filin was opening the gate to his residence when a masked man called out his name and threw the contents of a bottle in his face. After the attack he was able to see out of one eye but not the other, Ms. Timergazina said.
An official at the theater told Interfax that he would be sent overseas, probably to Germany or Israel, for treatment. Doctors have said his recovery may take as long as six months.
The Bolshoi has a reputation for intrigue and outsized emotions, but Ms. Novikova said she never imagined that it could lead to violence.
"Sergei was constantly receiving threats after he took up this post and his predecessors were under attack before him," she told Russia's Channel One. "We never thought that this war for roles -- and not for real estate or for oil -- could reach such a criminal level. And we always wanted to believe that people connected with theater would have a minimal level of morality. That's why this is an absolutely frightening story."
Mr. Filin signed a five-year contract as director of the Bolshoi in 2011. Among his first big decisions was to hire David Hallberg as a principal dancer -- the first American to hold that coveted status, which has traditionally gone to Russian-trained dancers. He suffered a setback when two of its stars, Natalia Osipova and Ivan Vasiliev, left the Bolshoi for a far lesser-known theater in St. Petersburg.
Mr. Filin's leadership has not stood out as especially controversial. But Anastasia Volochkova, a former Bolshoi ballerina, said his power to assign roles made him the focus of sometimes passionate resentment.
"Sergei didn't do anything he could be condemned for," she said in an interview with Ekho Moskvy, a radio station. "This position is, of course, a sweet one. The head of the ballet decides everything: what grants each artists receive, or maybe won't receive. Who will dance certain roles, and who won't dance them."
She added, "The cruelty of the ballet world has become surprisingly pathological."
One simmering conflict has involved Nikolai Tsiskaridze, a popular principal dancer who last year harshly criticized a recent reconstruction of the theater and has publicly clashed with its leadership since then. A group of Mr. Tsiskaridze's supporters petitioned President Vladimir V. Putin in November, requesting that Mr. Tsiskaridze be appointed director of the Bolshoi.
Aleksei Ratmansky, Mr. Filin's predecessor as the company's artistic director, wrote on Facebook that the incident was "not a coincidence" and wished Mr. Filin "swift recovery and courage."
"Many of the illnesses of the Bolshoi are one snowball -- that disgusting claque which is friendly with artists, ticket speculators and scalpers, half-crazy fans who are ready to slit the throats of their idol's competitors, cynical hackers, lies in the press and scandalous interviews of people working there," he wrote. "The cause of it is the lack of theatrical ethics, which were gradually destroyed in the Bolshoi by specific people. This is the real trouble of this great theater."
Ms. Novikova said Mr. Filin met earlier on Thursday with Anatoly Iksanov, the theater's director, and discussed the hacking attacks and other threats. She said Mr. Filin's personal e-mail account was penetrated and personal correspondence was published in an attempt to discredit him in the eyes of the theater's leadership, a tactic that was also used against Mr. Filin's predecessor.
When this did not prove effective, she said, "it looks like they took one step further, but one step that was too harsh."
News of the attack rippled through Moscow, a ballet-loving city whose elite converged in 2011 to celebrate the theater's reopening after a six-year restoration. Natalya Timakova, the spokeswoman for Prime Minister Dmitri A. Medvedev, wrote on Facebook that she hoped Mr. Filin would recover and "forget everything that happened today, like a bad dream."
And Ms. Volochkova, the ballerina, who clashed publicly with the Bolshoi leadership in 2003 after she was dismissed over her weight, said the crime spoke to a degradation of Russian society.
"It surprises me that there was a time when there were duels -- people fought with swords, or settled their relations in a real, noble way," she said in the radio interview. "When it gets to the point where you can just splash acid, or kill a person, it's so low."
"I think the end of the world has already arrived in this land," she added.
Sophia Kishkovsky contributed reporting from New York.
This article originally appeared in The New York Times.