A3 981 then GQ 670 at Athens
Sofia → Athens → Istanbul
Timetable, Athens time
12:20A3 981 from Sofia at the gate
07:00GQ 670 to Istanbul leaves the gate
18 h 40 apart on the timetable, overnight
GQ 670 leaves 18 h 40 after A3 981 arrives on the timetable: more than half a day, so not a connection we count.