 In that same year he later lost the belt to Jong-Kwon Baek, and in 2002 challenged Yodsanan Sor Nanthachai for the vacant WBA super featherweight title, but lost by decision.He later moved up to lightweight and in 2004 fought Miguel Callist for the vacant WBA lightweight title, winning by TKO.Sim was outboxed and lost his belt in his next fight against Juan Diaz.