Rubuta ci gaba don wannan sakin layi - Mantzaris ya zama memba na manyan 'yan wasan kwallon kwando na Girka a shekara ta 2011. Ya kasance memba na manyan kungiyoyin kwallon kafa na Girka da suka buga a 2012 FIBA World Olympic Qualifying Tournament, da 2014 FIBA World Cup, da kuma EuroBasket 2015. Ya kuma taka leda a gasar cin kofin Olympics ta FIBA ta 2016 a Turin.
, da kuma a EuroBasket 2017.