Maslennikow started in 1991 for the first time in a national competition. In January 2002 he made his international debut in the Nordic Combined B World Cup. At the Junior World Championships in Schonach in 2002 , he and the team reached 11th place and 37th place in Gundersen. Even at the Nordic World Ski Championships 2003 in Val di Fiemme , he could not achieve a placement in the top forty in the individual competitions. On November 30, 2003 he made his debut in the Nordic Combined World Cup in Kuusamo . However, he remained unsuccessful in the first competitions and started so on in the B World Cup. It was not until the 2004/05 season that he reached the points in the first competitions. He finished the season in 24th place in the overall World Cup standings. In the sprint world cup he reached the 28th place.
At the Nordic World Ski Championships in 2005 he was again unable to achieve any top placements. At the Winter Universiade 2005 in Innsbruck he won silver in the sprint. At the 2006 Winter Olympics in Turin , he surprisingly reached 10th place in Gundersen. In the sprint he finished 43rd. With the team he came in 9th place. A year later he won the gold medal with the team at the 2007 Winter Universiade in Pragelato . In the sprint he just missed the medal ranks with fourth place. A short time later he reached 21st place in sprint at the Nordic World Ski Championships 2007 in Sapporo and 33rd place in Gundersen.
In the World Cup, he rarely made it into the points. So he could not repeat his placement of the 2004/05 season. Even at the Nordic World Ski Championships in Liberec in 2009 , he could not achieve a placement in the top twenty in the individual competitions. In the team competition, the team reached 10th place. At the 2010 Winter Olympics in Vancouver he was again unsuccessful with a 36th place in the individual on the large hill and 43rd in the individual on the normal hill.
After a last World Cup race in February 2012 in Almaty , in which he was 38th, Maslennikow ended his active sports career.
Russia
2006 Turin
2010 Vancouver
2005 Oberstdorf
2007 Sapporo
2009 Liberec
2011 Oslo