Best way to keep focus in pool (billiards) match?

In my pool (billiards) league I can often run 4-5 maybe even 6 . But I tend to lose my focus as I get closer to the 8ball. I have tried slowing my pace and even not thinking of my leave. I have even tried to focus on ONLY my current shot and yet I still seem to lose focus. Anyone have any suggestions on how I can maintain my focus?