The Bolshoi Theatre has seen many nasty rivalries in the past, but the acid attack on Sergei Filin may take professional intrigue and jealousy to a whole new depth.

The stories about vengeance at the Bolshoi Ballet go back centuries: The rival who hid an alarm clock in the audience, timed to go off during Giselle's mad scene, or who threw a dead cat onto the stage at curtain in lieu of flowers. There are whispers of needles inserted in costumes, to be discovered in midpirouette, or - the worst - broken glass nestled in the tip of a toeshoe. But this ballet-loving city awoke recently to a special horror. A masked man had flung acid in the face of Sergei Filin, the artistic director of the Bolshoi, causing third-degree burns and severely damaging his eyes. Video from the hospital showed Filin's head covered entirely in bandages, with openings for his eyes and mouth, his eyelids grossly swollen.

Though police officials said they were exploring theories including disputes over money, Filin's colleagues at the Bolshoi said they suspected professional jealousy. In recent weeks Filin's tyres had been slashed, his car scratched, his two cellphones disabled, his personal email account hacked and private correspondence published, according to Bolshoi officials. On the day of the acid attack, Filin had met with the Bolshoi's general director, Anatoly Iksanov, and confided that he was beginning to worry about his children's safety.

"Sergei told me that he had the feeling that he was on the front line, " Iksanov said at a news conference. "I told him, 'Sergei, I've already been on the front line for the last two years, it is part of our profession, the profession of the leadership, so it's normal. '" Then Iksanov paused. "No, no, it's not normal, " he said.

The attack provoked a day of soul-searching. The Bolshoi is a revered place in Russia;when its historic stage reopened in 2011, after a six-year restoration, the country's elite arranged themselves in crimson-lined boxes, and hundreds of less fortunate people - cabdrivers and cleaners - stood on the street outside for hours on a cold, blustery night to watch the performance on a screen. The ballet's leadership has experienced poisonous infighting recently as a number of artistic directors have struggled to put their stamp on a deeply traditional company. Two years ago the company's director, Gennady Yanin, resigned after a message with a link showing sexually explicit pictures of someone who resembled him was sent to email addresses in Russia and elsewhere.

Gedeminas Taranda, who was a principal dancer at the Bolshoi during the Soviet era, said that there were always rival camps within the company, but that the attack on Filin had a viciousness that he and his contemporaries could not have imagined.

"Nothing like that happened in our times, " he said on a talk show. "We were ready to go out on the street, toe to toe, but it was impossible to think about anything like this. We could have gone and fought it out like real Russian people, although it was still ballet, and all that. "

Old and new have been colliding at the Bolshoi since the late 1980s, when upstart dancers rose up against the longtime artistic director, Yuri Grigorovich, and the rigid Soviet classicism he represented. He resigned in 1995, but his successors have not had an easy time of it.

Filin, who is 42, signed a five-year contract as artistic director in 2011. After the scandal of Yanin's departure, he was seen as "the political and cultural bridge that the Bolshoi needs", combining the pedigree of a Bolshoi dancer and a record as an innovator at Moscow's second-tier company, the Stanislavsky and Nemirovich-Danchenko Ballet, wrote Judith Mackrell, a dance critic for the British newspaper The Guardian.

Filin's leadership has not stood out as especially controversial, though he suffered a blow in 2011 when two of his stars, Natalia Osipova and Ivan Vasiliev, left the Bolshoi for a lesser-known company in St Petersburg, the Mikhailovsky Theatre. Anastasia Volochkova, a former Bolshoi ballerina, said his power to assign roles made him the focus of sometimes passionate resentment.

Katerina Novikova, the theatre's press secretary, said that Filin began receiving threats soon after he took his post. Dilyara Timergazina, his assistant and adviser, said they had become increasingly oppressive in recent weeks. She said a relative had offered to supply Filin with a bodyguard, but Filin refused.