He made ten appearances for Western Province U21 in the 2013 Under-21 Provincial Championship, scoring a brace of tries in his first start at this level in their final match of the regular season against the Sharks U21.
He then moved to the Western Province squad that participated in the 2014 Vodacom Cup, where he made his first class debut by starting their 16–8 victory in the opening round of the competition.
[5] Kôtze also scored his first career try in Round Five of the competition, a 65–29 victory over Kenyan invitational side Simba XV,[6] eventually making a total of 6 starts.
Kôtze was a key figure for the Western Province U21 side that participated in the 2014 Under-21 Provincial Championship, starting eleven of their fourteen matches during the competition, including their semi-final victory over Free State U21 – during which he scored one of seven tries during the season to help Western Province to a 41–17 victory[7] – and the final, where they lost 10–20 to the Blue Bulls U21s.
[8] In 2015, Kôtze was named in the wider training group of Super Rugby side the Stormers.