Panathinaikos failed to "finish off" the series against Valencia, and in fact twice at home despite having secured a 2-0 lead in Spain, losing 86-89 in Game 4.
Ergin Ataman's team will be forced into a Game 5, which will determine qualification for the Final Four in Athens.
This is the third consecutive season that the "Greens" have reached a fifth game to decide qualification.
First, in the 2023-24 season, when they managed to make it 3-2 in the series against Maccabi Tel Aviv in the fifth game, advance to the Final Four in Berlin, and lift the trophy.
This was followed by last year, where again with home-court advantage, Panathinaikos made it 3-2 against Anadolu Efes.
This time is different, however, as the "Trifylli" (shamrock) does not have the home-court advantage, but will travel to the Roig Arena for the coveted qualification.