AA 9866 then AA 4748 at O'Hare
Marquette → Chicago → Pittsburgh
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
09:45AA 4748 to Pittsburgh leaves the gate
23 h 15 apart on the timetable, overnight
AA 4748 leaves 23 h 15 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.