US ballet star David Hallberg was to perform Friday with the Bolshoi Ballet company after becoming the first American to join the troupe as a full member. Hallberg is to dance the role of Count Albert in the classical ballet \"Giselle\" alongside the formidably talented young Russian ballerina Natalia Osipova, the Bolshoi said. His presence is a massive boost for the Bolshoi, which is hoping the reopening of its historic main theatre last week after a six-year renovation will consolidate its reputation as one of the world\'s great ballet troupes. \"He has already danced in \'Giselle\' at the Bolshoi but then he was simply an invited artist,\" the head of the Bolshoi ballet, Sergei Filin, told the RIA Novosti news agency. \"David has been worrying since the morning about his debut as he feels a great responsibility to go on stage as a soloist of the Bolshoi Theatre,\" he said. Filin said that Hallberg was making every effort to dance in the manner of the Russian ballet school to \"correspond with the spirit and style of the Bolshoi Theatre.\" Whereas Russian dancers including Rudolf Nureyev and Mikhail Baryshnikov famously defected to the West from the Soviet Union, this is the first time that a Western dancer is to perform full time with the Bolshoi. Hallberg is one of the hottest properties in international ballet, famed for his technical brilliance as well as his film-star good looks that make him a prime example of the \"noble\" male dancer of classical ballets. Since 2005, he has been one of the main attractions of the American Ballet Theatre. Western dancers have on occasion in recent years made guest appearances with the Bolshoi and its main rival, the Mariinsky Theatre of Saint Petersburg. But in contrast to Western companies like London\'s Royal Ballet, the Russian theatres have until now drawn their troupes exclusively from Russia and the former Soviet Union.