TTT Riga led by as many as 10 points in the fourth quarter but weren't able to deliver the knockout punch as Fenerbahce claimed a valuable win on the road.
Cappie Pondexter had 23 points and Turkey national team center Nevriye Yilmaz scored 11 while also pulling down nine rebounds as the Turkish giants won 59-55.
Fenerbahce had plenty of chances to surrender in this one but they battled hard in the fourth quarter to earn their sixth win in eight Group A games.
TTT Riga will be wondering just how this victory escaped them.
Latvian national team playmaker Zane Eglite nailed a three-pointer with 6:05 remaining for a 51-41 lead, but Riga were outscored 18-4 the rest of the way.
And it was Pondexter who did most of the damage in the comeback for Fener.
Her three-ball cut the deficit to 51-47, and after a made jump shot by new signing Sviatlana Volnaya from Dynamo Moscow again reduced the arrears to four at 53-49, Pondexter struck again to make it 53-51.
Riga's new signing, Portuguese international and former Spartak Moscow Region playmaker Ticha Penicheiro, sank a jumper for a 55-51 lead with 1:51 remaining.
But a Pondexter three-ball pulled the Turkish team to within one and then her jump shot with 35 seconds to go gave Fener a 56-55 advantage.
Volnaya then paid dividends with her defense, stealing the ball from Tare which led Riga's Brazilian forward Micaela Martins Jacintho fouling Pondexter.
The former star at the Rutgers University made two free throws for a three-point lead just 15 seconds from the end.
Riga still had a chance to tie with a three-ball, but Jacintho missed from long range.
Penicheiro fouled Volnaya with two seconds remaining, and the Belarus star split two at the line as Fener won by four points.
Iciss Tillis finished with 13 points and 12 boards for TTT Riga, with Russian center Elizaveta Kityzina also scoring 13 in defeat.
Fenerbahce trail undefeated CSKA Moscow by two games.
Ainars Cukste, coach TTT Riga:
"This was a very painful and even stupid loss in the last minutes. There was no leader in the last minutes, everybody waited and our objectives for the last minutes weren`t achieved. We prepared for one-on-one defense but the opponents used zone during the last minutes. Pondexter created shooting positions for herself. Fenerbahce could only be happy with such player as Cappy. Now we have to win on the road to remain in the battle for qualification. Today it was even harder to play than in Istanbul, the teams played better basketball than two months ago and the game was far more aggressive."
Ticha Penicheiro, player TTT Riga:
"We played for 37 minutes, during the last three minutes we lost the game and it was disappointing. Pondexter played great in the second half, she was stubborn in defense and she can do just about everything on the court. Fenerbahce switched to zone defense in the end and we lost. If you play only for 39 minutes, you have less chances to succeed."
Zafer Kalaycioglu, coach Fenerbahce:
"We are really lucky to win this game and Riga was unlucky. We didn't have enough concentration for most of the game but we played great in the last minutes. We pushed a zone defense and maybe Riga wasn`t ready to fight it. This is our second road win, now we are guaranteed to finish second in the group."
Cappie Pondexter, player Fenerbahce:
"It was a competitive game. In fact, this was a battle for the second place in Group A. We Riga is a good team, well coached and it took time to break through. However, for me it wasn`t hard to get back into the game after the Christmas break."