Grobbelaar was born and grew up in
Paarl. He attended and played rugby for
Paarl Gymnasium and was selected for the squad for the 2015 Under-18
Craven Week tournament. His team won the main match at the tournament held in
Stellenbosch, beating 95–0 in the final. After the Craven Week tournament, Grobbelaar was selected for the
South Africa Schools squad that participated in the 2015 Under-18 International Series. He started all three of their matches; he scored a try in their 42–11 win over Wales in their first match and helped his team to wins over
France and
England in the other two. After school, he moved to
Pretoria to join the academy. He played for them at Under-19 level in 2016, and the following year he was selected in the
South Africa Under-20 squad for the
2017 World Rugby Under 20 Championship. He started all five matches at the tournament, helping his side to a 23–23 draw against
France, a 38–14 victory over
Georgia and a 72–14 win over
Argentina (a match in which Grobbelaar scored two of South Africa's eleven tries) as South Africa topped
Pool C to qualify for the semi-finals. A 22–24 defeat to
England in the semi-finals ended their hopes of winning the competition, but they bounced back in the third-place play-off to beat France 37–15, with Grobbelaar scoring a further two tries. He made his domestic first class debut shortly after his return to South Africa, coming on as a replacement in the ' 54–22 victory over the in their
2017 Currie Cup Premier Division Round Three match. He became a regular on the Blue Bulls' replacement bench during the season, making a total of ten appearances. He also scored three tries during the season, in matches against , the and the . In 2018, Grobbelaar was included in the squad for their final match of the
2018 Super Rugby season against trans-
Jukskei rivals the , and he made his
Super Rugby debut by coming on as a second half replacement. ==Honours==