Ka cika wannan jumla: Diamantidis ya kasance cikin 'yan wasan ƙasar Girka da suka yi gasa a Wasannin Olympics na Athens na shekara ta 2004. An kuma zaɓe shi don buga wasan ƙwallon ƙafa na ƙasar Girka don gasar zakarun Turai.
Wasannin Olympics na Beijing na shekara ta 2008. Girka ta gama a matsayi na biyar a duka wasannin biyu, inda ta yi rashin nasara sau biyu ga Argentina a wasan kusa da na karshe na gasar.