Did the MAA-SIN-NRT-SFO on Jan 1 with a one hour fifteen minute connect time and had plenty of time left, even with checked luggage. My luggage was tagged all the way to SFO, but I could not get a UA boarding pass in Chennai.

The only thing I had to do in SIN is to take the train to the UA terminal and get my SIN-NRT-SFO boarding pass at the UA desk.