Russian Ballerina Natalia Osipova Joins London's Royal Ballet LONDON - It was only 18 months ago that the Russian ballerina, Natalia Osipova, shocked the dance world by leaving the Bolshoi Ballet, where she was considered a major star, to join the lesser-known Mikhailovsky Ballet in St. Petersburg. But on Monday, the Royal Opera House announced that Ms. Osipova will join the Royal Ballet as a principal dancer for the 2013-14 season. The announcement comes hot on the heels of Ms. Osipova's wholesale conquest of this city during the Mikhailovsky's recent two-week engagement here. In an interview with the Russian newspaper, "Kommersant," Ms. Osipova gave the same reason for her move from the Mikhailovsky to the Royal as she did for her move from the Bolshoi to the Mikhailovsky: Repertoire. I really would like to soak up the choreography that I haven't yet mastered - ballets by Frederick Ashton, Kenneth MacMillan. It's great that I can work with the company's chief guest choreographers - with Christopher Wheeldon and Wayne McGregor, as well as the stunning young choreographer Liam Scarlett. This is a great chance. One controversial aspect of Ms. Osipova's move to the Royal Ballet is how it will affect her relationship with American Ballet Theater, where she also holds a principal dancer contract, with commitments running through the 2014 season. Sergei Danilian, Ms. Osipova's agent, was quoted on Monday in "Kommersant," saying that Kevin McKenzie, the artistic director of Ballet Theater "did not hide his frustration, as the spring season in London coincides with New York, but this is a new reality that will have to be dealt with somehow. It is difficult to say how it will be settled, but the fact remains that there are conflicting interests, and we will hope for the wisdom of the leaders of the two companies to settle it. In the "Kommersant" interview, Ms. Osipova, who has previously danced as a guest artist with the Royal Ballet, said that she will go on performing with the Mikhailovsky Ballet, as a guest artist, and that she will continue to dance with Ballet Theater. ABT is a part of my life, but I am happy with the relationship that I have with them. I go there, dance at the Metropolitan, and leave," she said, according to a translation of the interview. It will remain to be seen if Ms. Osipova will put down deeper roots in London, or whether the Royal Ballet appointment - which begins with a performance in "Romeo and Juliet" opposite Carlos Acosta in the fall - means little more than a similar string of guest appearances. The ballerina's on- and off-stage partner, Ivan Vasiliev, who is also a star, and who left the Bolshoi for the Mikhailovsky with her, has not been asked to join the Royal Ballet, but will also move to London, "Kommersant" reports.