Ku dhameystir weedha soo socota: Kostitsyn wuxuu u muuqday kulankiisii labaad ee U-20
2002 Horyaalka Hockey-ga Barafka ee Junior-ka Adduunka wuxuuna dhaliyay seddex gool si uu uga caawiyo Belarus inay sii ahaato horyaalka ugu sareeya. Kadib sanadkaas, Kostitsyn wuxuu ku soo laabtay horyaalka ugu sarreeya ee 2002 IIHF World U18 Championships, isagoo diiwaan galiyay 10 dhibcood siddeed ciyaarood wuxuuna gacan ka geystay hoggaaminta Belarus si uu u dhammeeyo kaalinta shanaad. Kostitsyn wuxuu ka qeyb galay tartankiisii saddexaad ee ka hooseeya 20 ee 2003 World Junior Ice Hockey Championships, wuxuu diiwaan geliyay laba gool iyo hal caawin, laakiin wuxuu la galay Belarus ilaa Division-I 2004. Isaga oo ka ciyaaraya heerka labaad, wuxuu dhaliyay shan gool iyo 10 dhibcood shan kulan si uu uga caawiyo Belarus inay ku soo laabato horyaalka ugu sareeya 2005, halkaas oo uu ka dhaliyay shan dhibcood kulankiisii shanaad iyo kii ugu dambeeyay ee World Juniors.