Final Round Pairing order of precedence question

Watching the finish of the 3rd round tonight (2015 U.S. Open), there are 4 guys tied at for 1st at -4. I know that normal order of precedence is the order in which the golfers finished their round. Obviously Jason Day finished well ahead of the others, so I understand that he would be in the final pairing. Dustin Johnson and Branden Grace were in the same group (and both finished at -4), but Johnson tapped in before Grace, so I presumed Johnson would be in the final pairing (I believe Johnson actually is in the final pairing but continue reading...). However I did some research and read that if two players finish with the same score and played in the same group, the order reverts back to the player who had a better score to start the day (see Tiger Woods/Sergio Garcia 2013 Players I believe). In this case though, both Dustin and Branden started the day with the same score. So I have a question?

1) Would the next tie breaker in ordering revert back to who finished first in round 2,or would it be the player that had a better score going in to round 2?

Looking back, it can't be who was first-in for the previous round (round 2), since Grace finished 4-5 hours before Johnson, because I can now see that it is definitely Johnson who will be in the final pairing. So I guess the question is, is it in fact the player that the better score going into round 2, or is there some other criteria?

The tiebreaker works is this: the player who had the honors at the the start of the day will be the one that it put in a later pairing.

So Johnson must have teed off first on day 3.