Bulgaria matched Hungary's efforts by becoming the only other team to make it through the preliminary round with a 100% record.
But while Hungary overwhelmed their opponents on Sunday, Bulgaria were made to struggle by Greece before claiming a 53-52 win.
After trailing 17-15 after the first period, Bulgaria hit back superbly to take a 32-25 lead at the midway point.
Greece trimmed that advantage to four points at 40-36 heading into the final period but the only time they got within three points of their opponents was in the final 23 seconds when Anastassia Gkotzi and Nafsika Stavridou made one successful free throw each to complete the scoring.
Power forward Pelagia Papamichail was Greece's leading light with a game-high 15 points and four rebounds while Radostina Slavova top-scored for the victorious Bulgarians with 10 points.
Even though they ended on the losing side against Bulgaria, Greece still finished in second spot in Group A with the Czech Republic downing Finland 79-64 to take third place.