Tsenov made his first major international appearance at the 2011 IAAF World Cross Country Championships, where he placed 86th out of 106 finishers in the junior men's 8K race. At the 2012 World Junior Championships in Athletics, he competed in the men's 3000-metre steeplechase, where he narrowly missed qualification to the final round. At the 2012 European Cross Country Championships, he finished second overall in the junior men's race behind Poland's Szymon Kulka, winning Bulgaria's first ever medal in the European Cross Country Championships. At the 2013 European Cross Country Championships, he finished second overall again, except this time in a lengthier-distance U23 race. In 2014, he placed ninth of fifteen competitors in the finals of the men's 3000-meter steeplechase at the 2014 European Athletics Championships.