Ruslan Nosirov first appeared in 2003 at the Junior World Championships in Forni Avoltri . His best result in four starts was 17th. A year later he finished again in four starts in Osrblie between nine and twelve. The 2005 Junior World Championships in Muonio were even more successful . He finished tenth in the sprint, fifth in the pursuit and sixth in the mass start. With the season, which also included Murod Hodjibayev and Anusar Yunusov, he won the silver medal. The greatest successes at the Junior World Championships reached Nosirov in 2006 in Ufa . There he won gold in the sprint, silver in the pursuit and also finished fifth in the mass start. Another medal, silver in the mass start, was also added in 2007 in Otepää . The Uzbek finished sixth in the sprint. He was also used in the mixed relay. With Dilafruz Imomhusanova , Zarema Mamedova and Anusar Yunusov he missed another medal in fourth.