Fenerbahce lost 74-79 at home to Spanish squad Baskonia Vitoria Gasteiz at Istanbul’s Ulker Sports Arena.
The loss dropped Fenerbahce to 16-9 for the season but it managed to retain its fourth place in the standings.
Baskonia improved to 14-11 and remains in the playoffs race after Round 25.
A 19-point output by Shane Larking helped spark Baskonia’s victory.
Bogdan Bogdanovic's 26 points and 8 assists was not enough for Fenerbahce who was hampered by the absence of center Ekpe Udoh.
The defeat snaps Fenerbahce's five-game home winning streak.
In other play, Galatasaray Odeabank was no match for regular season leader CSKA Moscow as the Russian team won handily 85-69.
Nando de Colo was on top form, scoring 22 points for CSKA and Vladimir Micov's netted 18 points for Galatasaray.
CSKA improved to 19-6 for season and Galatasaray dropped to 8-17, falling another step behind in the playoffs hunt.
On Friday, Anadolu Efes will look to continue its good play against Germany's Brose Bamberg in Istanbul while another Turkish team, Darussafaka Dogus Istanbul, will go to Piraeus to square off against Olympiacos.
In other games Thursday, Zalgiris Kaunas topped Panathinaikos Superfoods 64-58; Maccabi Fox Tel Aviv beat EA7 Emporio Armani Milano 92-82 and Barcelona Lassa handled UNICS Kazan 70-62.