Apollon Patras is the second team to go down from the Basket League after Doxa Lefkadas, while Aris snatched the fourth spot of the regular season right at the end, on Thursday.
In a dramatic last round of games Apollon defeated visiting Lavrio 72-61 in Patra, but its crosstown rival, Promitheas was unable to stop Korivos Amaliadas from scoring a precious home win that preserved its top-flight status for another year.
Korivos triumphed 66-62 to stay up and send Apollon down, amid wild celebrations at Amaliada, with credit going to its players and coach Dinos Kalabakos for operating on a shoestring budget.
On the other hand Apollon, the historic team of Patra, has returned to the A2 division after five seasons. This was despite having NBA legend John Stockton at the stands watching his 27-year-old son Michael play for the host at the Perivola court.
Aris came from 10 points down at half-time to beat third-placed AEK 81-77 in Thessaloniki to snatch the fourth spot from PAOK that got thrashed 102-58 in Athens by Panathinaikos.
The Greens finished level on points with Olympiakos, but the Reds have obtained the home advantage for all of the play-offs on a superior head-to-head record. On Thursday they mauled visiting Kymi 93-45.
Rethymno beat relegated Doxa 80-67 away to finish sixth, ahead of Kolossos that saw off 73-53 on Rhodes.
In the first round of the play-offs fifth PAOK will meet eighth Lavrio and Rethymno will clash with Kolossos, in best-of-three series starting on April 19.