While the eight lower placed teams from the 2016–17 Greek Basket League season; along with all of the teams from the 2nd-tier level Greek A2 Basket League's 2017–18 season, and the 3rd-tier level Greek B Basket League's 2017–18 season, played in preliminary rounds, competing for the other two quarterfinals places.

The quarterfinals and onward rounds were played under a single elimination format.

Saturday 2018–09–15 Wednesday 2018–09–19 Note: Aiolos Trikalon decided to forfeit their game against Faiakas Kerkyras.

Saturday 22 or Sunday 2018–09–23 Wednesday 2018–09–26 Note: Olympiacos decided to forfeit their semifinals game versus Panathinaikos at halftime, over reffing disputes.

Referees: Papapetrou, Karakatsounis, Tsarouchas Panathinaikos (Pitino): Calathes 19, Langford 17, Gist 14, Thomas 12, Papapetrou 10, Antetokounmpo 5, Mitoglou 2, Payne, Kilpatrick, Lekavičius, Vougioukas, Papagiannis PAOK (Papatheodorou): Hatcher 23, Goss 15, Margaritis 13, Garrett 10, Jones 9, Zaras 3, Jefferson, Tepić, Chrysikopoulos, Koniaris, Tsochlas, Schizas