Panathinaikos will pay €500,000 to his former club during the next three seasons, along with a 25% next transfer percentage and some appearances and targets bonus, which could increase the cost of 23-year-old international's move to the team of manager Marinos Ouzounidis to €700,000.

PAOK are offering Panathinaikos €1.5 million for Kourbelis, including the services of Ergys Kaçe, Giannis Mystakidis and Dimitris Konstantinidis for the second half of this season, but the player is reluctant for this transfer, besides the annual fee of €450,000.

[11] On 1 September 2018, he scored his first goal for the club in all competitions, with a penalty kick after 21-year-old winger Tasos Chatzigiovanis was fouled in the box by Lamia's goalscorer Daniel Adejo, sealing a 3–1 home win game.

[14] On 22 January 2020, the Greek international defender let fly with an unstoppable shot from just outside the penalty area which left Balázs Megyeri no chance, in a hammering 3–0 home win game against Atromitos.

[15] On 1 July 2020, the Greece international midfielder made a vital interception before striding forward and beat Fabian Ehmann with four minutes to go to the interval, giving the lead in a 2–0 home win game against Aris.

On the same match, he officially debuted in the Greece national team coming on as a late substitute in a 0–0 away draw against Bosnia and Herzegovina for the 2018 FIFA World Cup qualifications.