UA 3532 then AA 4915 at O'Hare
Knoxville → Chicago → Lexington
Timetable, Chicago time
18:43UA 3532 from Knoxville at the gate
15:49AA 4915 to Lexington leaves the gate
21 h 06 apart on the timetable, overnight
AA 4915 leaves 21 h 06 after UA 3532 arrives on the timetable: more than half a day, so not a connection we count.