Trying to throw a diamond from dummy and ruff three diamonds in dummy won't work - they''ll switch to trumps on winning
♣A. For the same reason (and some others) I can't ruff the hearts good. That leaves the diamond finesse.
There's no reason to play LHO for
♦K, and playing RHO for
♦K requires less elsewhere, so I'm going to run
♦J. I should draw at least one trump first.
One trump caters for someone being 1-1 in the pointed suits. If I draw only one trump, I go off when someone has one diamond and two spades.
Should I draw a second trump? After
♥A throwing a diamond,
♠J,
♠K,
♦J,
♦10,
♦ ruff, I'm OK if trumps were 3-2 - ruff a heart, draw the trump, knock out the ace of clubs - or if diamonds were 3-3 - knock out
♣A before drawing the remaining trumps. If trumps are 4-1 and diamonds 4-2 the other way, I have to knock out
♣A and hope that it's won by the hand with the trumps, who can't hurt me.
These seem very close to me, so I had to seek electronic assistance.
Richard Pavlicek's dual suit break calculator tells me that:
- 4-2 in the pointed suits occurs 9.28% of the time. It's only a problem if
♣A is in the wrong hand, so drawing two trumps fails 4.64% of the time.
- 2-1 or 2-0 in the pointed suits is less common, at 3.72%. This is when not drawing a second trump fails.
I should just have written "Agree with Patapon" and saved myself some time.