As brown I was leading yellow 5-2/7 and had this tricky 4-2 roll to play.  It should be readily apparent that yellow is poised to complete a six-prime, and brown needs to urgently address this threat.  It may seem natural for brown to step up to yellow’s 5-point with the four, but this simply invites an attack after which yellow should have plenty of time to escape the back checker.  I can also consider trying to aggressively counter-prime by slotting the bar with 13/7 (this was my actual play after expending a lot of energy and a few minutes on my clock).  The idea behind this play is to duplicate the sixes that yellow needs to escape, and also may need to secure the five-point.  If missed, I should now be a favorite to construct a six prime of my own.  I also considered the unconventional play of breaking my home board to hit on the one-point, but ultimately rejected this notion as it might invite the cube and a costly gammon which could propel my opponent to the Crawford game.  Surprisingly, a simulation reveals that any play which doesn’t involve hitting is a blunder!  While there are several possible alternatives that include hitting, 8/4, 3/1* offers the right amount of diversification if yellow should be unable to enter from the bar.  Volunteering two blots may seem suicidal, but it provides a direct winning path for brown and may even include a fair number of gammons that could end the match. This fact raises another fascinating point.  If brown hits, yellow should definitely turn the cube to leverage the value of their own gammons while also killing the value of gammons for brown (as a doubled cube already wins the match for brown).  Ironically, my slotting play of 13/7 may stave off my opponent’s cube as it leaves yellow with a more borderline doubling decision – although it is a clearly inferior play from a match-winning-chance perspective.