How strong is a six-point prime? Not always as strong as it seems. In the position above Black has just played 14/9, 6/4* and White now doubles. What should Black do?

Many players would drop this without much thought reasoning thus: I have one man stuck behind a full prime and White is shooting at a second blot from the bar. If he hits that one he may well hit my other blot on my 9-point as well and I will probably lose a gammon. No thank you very much, I'll pass this one, give up a point and get on to the next game.

The more astute player will realise that the next roll is critical and examine the possibilities more closely. His analysis might be: 16 shots hit (any 4 plus 13, 23, and 22), after which I am certainly in trouble, but the position still has plenty of play in it. The gammon threat is not that strong as I am likely to anchor in White's board if I am hit. What if White doesn't hit, and rolls, for example, 51 (played bar/24, 15/10)? In that case I am favourite to complete my own six-point prime and it is White who will be in trouble as he is likely to have to give up his prime before I give up mine. As White is not favourite to hit this certainly looks like a take to me.

This latter analysis is the correct one and rollouts show that Black will win this position 40 per cent of the time. It is White's initial double that is borderline but justified because the position is so volatile.

The lesson to be learnt here is not to be frightened by the apparent strength of your opponent's position. You must consider all aspects of the position before making your decision. Sometimes, as here, it is necessary to do a detailed analysis of the next sequence of rolls.