Mamleev won the Junior World Championship in Poland in 1994 with the Russian relay. In 1995 he won silver and bronze at the Junior World Championships in Denmark. Two years later, Mamleev started for the first time in a men's world championship. His first top 10 placement in an individual competition he reached at the 2001 World Championships in Tampere when he was sixth in the sprint. In 2002 he won the European Championship in the middle distance, the 2002 World Cup season he finished second behind the Norwegian Bjørnar Valstad . In 2004 in Sweden he was runner-up in the Russian relay together with Andrei Chramow and Valentin Novikow . In the spring of 2004, he also married Sabine Rottensteiner, a South Tyrolean - a former orienteer - and therefore moved to Italy. Mamleev also decided to start for Italy from now on. When he received his Italian passport in the summer of 2006, he started for Italy for the first time at the 2006 World Championships in Denmark. In 2009 at the World Championships in Miskolc , Hungary , he was third on the long distance behind the winner Daniel Hubmann from Switzerland and the French Thierry Gueorgiou . He won the first medal at an orienteering world championship for Italy. However, the medal was accompanied by protests. The Finnish delegation submitted an official protest that Mamleev is said to have run after Daniel Hubmann, who started four minutes after him, after the overhaul. The protest was ultimately rejected by two to three votes.
Mamleev also starts in mountain runs, long-distance and marathon events. He is a member of SC Meran and competes in international orienteering races such as the Jukola for the Swedish club OK Orion . Starting for Orion, he won the Swedish long-distance championship in 2003.
