Featuring the world-famous Placido Domingo, now more a baritone than tenor at 73, and Russian soprano sensation Anna Netrebko, demand for the premiere outstripped supply five times over.
Directed by Alvis Hermanis, conducted by Daniele Gatti and also starring Canadian contralto Marie-Nicole Lemieux, five further showings over the next two weeks are also sold out.
Other expected big hits among the 270 performances at the festival, this year with a war theme for the 1914 centenary, include pianist Lang Lang and conductor Sir Simon Rattle.
But not all the tickets -- some costing hundreds of euros (dollars) -- for the month-long extravaganza of opera, classical music and drama in Mozart's native city sell like hot cakes.
The annual shindig, in its 94th edition, is facing budget strains with too few spectators in recent years to cover the sometimes exorbitant costs of singers, sets, musicians and costumes.
This is despite last year's edition shifting 287,000 tickets and attracting record levels of corporate sponsorship.
Festival director Helga Rabl-Stadler has promised belt-tightening with fewer brand new productions and more recycled old ones in the future. She also wants more public money.
"I cannot stay silent any longer ... We need substantially more funding," she said in April. "What is at stake here is the very existence of the Salzburg Festival."
- Night at the museum -
"Il Trovatore" was last seen in Salzburg in 1963 under legendary Austrian conductor Herbert von Karajan, giving the class of 2014 big shoes to fill for what is anyway a challenging opera to stage.
"The music is from the 19th century, the story takes place in the 15th century and the audience is from the 21st century," Latvian director Hermanis told a news conference.
"As director I have to take these three perspectives into account."
His solution has been to set "Il Trovatore" -- a tale of love, war and Gypsy curses -- in a library at night where magic is at play, not unlike the 2006 Hollywood caper "Night at the Museum".
"A museum is like a time machine that brings the past back to life and awakens nostalgia for disappearing history," Hermanis said. "Time and space dissolve".
Hermanis "gives us great liberty," Lemieux told AFP. "He is someone who lets the singer do a lot of exploring. He sets a very precise outline but lets us be free inside that".
The production also calls on the performers not just to sing well, said Domingo, who made his Salzburg debut -- under von Karajan -- way back in 1975 in Verdi's "Don Carlos".
"On the stage we have to make the drama palpable. For the feeling, the role of acting is just as important as the music and the quality of the singing," the Spaniard told a news conference.
The Salzburg Festival, in western Austria, runs until August 31.
Its website is: http://www.salzburgerfestspiele.at/summer