Twice blocked by striking musicians and stagehands, Daniel Barenboim makes his debut in Milan as La Scala's principal visiting conductor Friday night with a gala premiere of Tristan und Isolde. Opening the season with Wagner on Verdi turf might seem a provocation. But Barenboim's six-season arrangement with La Scala will be an exercise in cross-fertilizing Italian and German operatic traditions as he wings between Milan and Berlin, where he is the Staatsoper's music director. "It is not an act of globalization but it is an act of cosmopolitan thinking," Barenboim said in an interview between rehearsals. This season, Barenboim will conduct Tristan and Prokofiev's treatment of Dostoevsky's The Gambler, as well perform the Beethoven sonatas for piano. The mixing of styles will reach a peak when La Scala and the Staatsoper execute a major co-production of Wagner's Ring Cycle in 2010-11. In fact, Wagner is not entirely foreign to La Scala's tiered balconies. His works are second only to Verdi in opening La Scala's seasons: 17 times dating to the 1889 performance of Die Meistersinger von Nuernberg to 1998's Goetterdaemmerung. Tristan, however, has not been among them. "Of all the Wagner operas, Tristan is the one opera that Wagner-haters like, even those who find the Ring intolerable, too Germanic, or whatever it is," Barenboim said. One might assume Barenboim was behind Wagner's prominent return to La Scala, where the German composer's work went silent for a half-century from 1932 largely because of the stigma cast on him by the fact he was Hitler's favorite composer. The Argentine-born Jewish conductor advocates separating Wagner's glorious music from the taint of Nazi admiration - and he has flouted an informal ban on Wagner in his adopted country Israel. But Barenboim says it was La Scala manager Stephane Lissner following the orchestra mutiny that led to Riccardo Muti's 2005 departure - who lured Barenboim to La Scala with the prospect of fulfilling one of his dream Wagner projects. Lissner "knew that if he offered me Tristan with (theater director) Patrice Chereau I could never say no, because this is something Patrice and I have been trying to do together for the last 26 years. And it had been canceled twice, in Bayreuth." No musical director has been named in Muti's place. Rather, Barenboim is chief among the guest conductors, including Daniele Gatti and Riccardo Chailly. The position is deliberately hazy, with Barenboim carrying the informal honorific title "Maestro of La Scala." Barenboim very nearly risked seeing this long-sought collaboration canceled again, this time due to labor tensions. La Scala's 800 employees, from musicians to stagehands, called a pair of walkouts in November, forcing the cancellation of two performances of Verdi's Requiem. The intervention of Culture Minister Francesco Rutelli dispelled the strike threat hanging over the gala premiere, the social event of the Milan cultural calendar, though no contract settlement has been reached. Barenboim said he had an instant chemistry with the La Scala orchestra - which became evident to both sides two years ago when he returned to opera house after a 30-year absence. He praises its musicians for their curiosity. He also knows La Scala's audiences can be savage in their search for purity - particularly those who frequent the upper tiers of La Scala's balconies known as the "loggionisti." Last year, their boos drove tenor Roberto Alagna from the stage during Aida. This year, British tenor Ian Storey as Tristan and German mezzo-soprano Waltraud Meier as Isolde will be put to the test. "Audiences of La Scala react differently to Aida than an audience in the Staatsoper in Berlin. No question about it," Barenboim said. "I think in Germany they would be much more tolerant of a slight vocal deficiency if the expression was there. And in Italy they would be a lot more tolerant for lack of expression if the beauty of the tone was there."