CSKA Moscow suffered their first home defeat of the Euroleague campaign, as Nemanja Bjelica led Fenerbahce Ulker to victory, while Olympiacos took advantage on Friday.
Bjelica produced a double-double for the visitors as they stunned CSKA 81-75 in Moscow, while Olympiacos defeated Unicaja 77-72 to claim top spot in Group F.
CSKA had not lost in nine matches in Moscow in the 2014-15 Euroleague season but struggled to deal with Fenerbahce early, as the visitors led 17-10 at the end of the first quarter.
The hosts reduced Fenerbahce's lead to just two points by half-time and one with a quarter to play as they took control in the middle stages, but their guests from Turkey won the final term 22-17 to prevail by six points.
Bjelica (11 points, 13 rebounds) was critical to Fenerbahce's victory, while Andrew Goudelock and Jan Vesely both scored 14 points for the winners.
Nando de Colo scored a game-high 18 points for CSKA.
In Greece, Vassilis Spanoulis (18 points, 10 assists) notched a double-double for Olympiacos in their five-point victory over Unicaja.
The win saw Olympiacos move to a 7-1 win-loss record, moving past previous leaders CSKA (6-2), with the Russians also dropping below Fenerbahce on points difference in the Group F standings.
Another Istanbul-based club - Anadolu Efes - sit fourth with a 4-4 record, after they lost 87-84 at home to Laboral Kutxa.
The Spanish visitors set up their win with a 25-13 opening quarter with Fernando San Emeterio ending the match with 22 points for Laboral Kutxa, while Colton Iverson (17 points, 11 rebounds) produced a double-double.
In Spain, Barcelona needed overtime to defeat Alba Berlin 92-82, with the home side outscoring their German guests 15-5 in the extra period.