UA 3851 then UA 751 at San Francisco
Rio De Janeiro → San Francisco → Las Vegas
Timetable, San Francisco time
17:41UA 3851 from Rio De Janeiro at the gate
16:50UA 751 to Las Vegas leaves the gatealso AC 4104, AZ 4491, EK 6366, VA 8191, NZ 9226
23 h 09 apart on the timetable, overnight
UA 751 leaves 23 h 09 after UA 3851 arrives on the timetable: more than half a day, so not a connection we count.