Roderick Blakney poured in a game-high 26 points as Maroussi held off RheinEnergie 57-55 to finish top of EuroCup Group G.
Both teams had already guaranteed their passage to the quarter-finals but top spot in the group was still at stake but it was the side coached by Greek legend Panagiotis Yannakis who emerged victorious.
Blakney contributed almost half of Maroussi's points on the night, with Aleksandar Nadjfeji (20 points) leading the scoring charts for the visitors.
Behind by five at the start of the second half, Maroussi managed to overturn the deficit with an 18-9 third-quarter run which put them 42-38 up going into the final 10 minutes.
And the hosts, one of the favourites to win the tournament, resisted a RheinEnergie push in the fourth quarter to claim victory.