Olympiakos went down at Galatasaray 79-74 on Thursday for its second defeat in the first round of the Euroleague that ended with the Reds topping their pool with eight wins in 10 games.
With nothing left to play for in Istanbul, as they had already won their group, the Greeks faced a motivated host who needed victory and eventually earned it despite playing without its fans.
Galatasaray advanced to the last 16 of the Euroleague and will be in the same group as Panathinaikos in the second round, having led 11-0 at the start and 20-18 after the first quarter.
Olympiakos responded and led by two at half-time (38-36), but its scoring problems in the third period allowed the Turks to advance 57-50 at the end of the quarter and then 63-52 in the fourth period, before the Reds came to within one point (69-68).
The host wanted the win more, and secured it in the end with a five-point margin, even though it only had seven players featuring throughout the match.
Matt Lojeski was the top scorer for Olympiakos with 22 points.
On Wednesday PAOK defeated Buducnost 81-76 in Podgorica to claim the second spot in its Eurocup group.