Western Province finished in third spot on the log to qualify for the semi-finals, where they met the Free State U19s and Zas scored for a third time against the same opposition in a 29–22 victory in Bloemfontein.
[9] In 2015, Zas was selected a 37-man South Africa Under-20 training squad[10] and started for them in a friendly match against a 2015 Varsity Cup Dream Team, scoring a try in a 31–24 victory.
[11] He was named in their squad to tour Argentina for a two-match series as preparation for the 2015 World Rugby Under 20 Championship.
[21] In 2016, Zas was included in a South Africa 'A' squad that played a two-match series against a touring England Saxons team.
[22] He was named in the starting line-up for their first match in Bloemfontein,[23] but ended on the losing side as the visitors ran out 32–24 winners.