At age thirty-four, Kejzar made his official debut for the 2000 Summer Olympics in Sydney, where he placed sixty-second out of a hundred runners in the men's marathon, with a time of 2:26:38, fourteen seconds behind Tanzania's Zebedayo Bayo. He displayed a stellar performance at the 2004 Summer Olympics in Athens, when he finished fifty-fourth in the marathon for the second time, posting his best Olympic career time of 2:23:34.