Born in Saransk, he won the 10 km youth section of the 2005 Russian Winter Walking Championships, then came a close second to Vladimir Akhmetov at the national junior championships. He and Akhmetov duelled at the 2005 World Youth Championships in Athletics and Morozov came out on top to win the world youth title over 10,000 m. The following year, he won the national junior winter title then won the junior race at the 2006 IAAF World Race Walking Cup. He was the leader early on at the 2006 World Junior Championships in Athletics, but collapsed mid-race and did not finish. In 2007 he had a series of wins over the 10K distance: he won the Russian junior winter title, then the 2007 European Race Walking Cup junior title, culminating in a gold medal at the 2007 European Athletics Junior Championships. He made his senior debut in September at the IAAF Race Walking Challenge Final in his native Saransk, but was disqualified for lifting.