A K x x x K x A x x x x x | ||
Lead: Q | x x A Q 10 9 x x A Q x x x |
The best play in the trump suit to keep your trump losers to 1 is a heart to the queen, not the 10 (in practice some people obviously took this line as they just barely made 4). The first line wins with Kxx or Kx in east, the second with Jxx or Jx in east. However, the first line has an extra edge as it also wins with Jx or KJ in either hand. However, this does not solve all problems. A diamond needs to be discarded on the club suit which means clubs need to be 3-3 to be ruffed out, which implies a 3-3 heart division. In case hearts are 4-2 some remote squeeze chances remain.
I saw another possibility which I took in actual play. Diamond king and ace followed by a diamond ruff. Then club ace and club ruff. Then came the supreme moment: heart ace followed by the queen. West showed up with the jack and the slam was made. This line reduces the chances of only one trump loser (only with Jx or KJ in trumps in east or west) but only requires diamonds to be 4-3.
It's difficult to estimate probabilities for both lines and say which one is best. Maybe, some of you can tell me?