Dee ihe na-aga n'ihu maka paragraf a - Mgbe ọ dị afọ 15, Markešević setịpụrụ ihe ndekọ mba nke 3000 mita maka afọ 15 na oge nke 8:51.58. Markešević mere egwuregwu mba ụwa mbụ ya na 2003 European Youth Summer Olympic Festival na Paris, France, ebe ọ kwụsịrị nke abụọ n'egwuregwu 3000 mita. Na 2005 IAAF World Cross Country Championships
, Markešević kwụsịrị n'ọnọdụ nke iri atọ na isii nke ndị 125 na-agwụcha n'ọsọ 8K nke ụmụ nwoke. Na ngwụcha afọ ahụ, ọ bịara nke atọ n'asọmpi ụmụ nwoke na-eto eto na 2005 European Cross Country Championship. Na 2006 European Cross Country Championships, Markešević tinyere na nke abụọ n'ozuzu megide asọmpi U23 dị oke egwu, na-emecha n'ihu Daniele Meucci na Yevgeny Rybakov.