Come up trumps

Dig someone out of a hole, or do something that turns the tide and turns the situation into a success, particularly at the last minute and when unexpected, with all hope lost.
Same as come through for someone in the clutch, only an older phrase, and more precise, better conveying the sense of "in the nick of time", and "unexpected".

Look at it like this- played out action movie scenario: there are three guys fighting. 2 vs 1. One of them gets knocked out cold, and then the guy that knocked him out pulls out a gun and is about to finish off the other guy. Just when he is about to pull the trigger and send him to kingdom come, he gets hit in the head/ shot in the back etc by someone, and we see that someone is the guy who was out cold.

He came up trumps.

My old junker broke down and left me stranded in the middle of nowhere, but this guy came up trumps and gave me a ride.
#come up trumps

This bully started pushing me around, but Daniel came up trumps just when I was about to get my ass kicked big time, and took him down a few pegs.