Kammala jumla mai zuwa: Khalifa ya yi gasa a Mauritania a wasannin Olympics na bazara guda biyu, da farko a Wasannin Olympics na 1988, inda ya yi gasa a tseren mita 5000 kuma ya gama na 17 a cikin zafinsa, amma bai cancanci zuwa zagaye na gaba ba. Shekaru hudu bayan haka a wasannin Olympics na 1992 ya shiga cikin
marathon amma bai gama ba.