Source: The duck-it list — part 1
In the movie, The Bucket List, Jack Nicholson and Morgan Freeman make a list of things they want to do before they “kick the bucket.”
Let’s look at some of the situations (it would take a book to talk about them all) where it is the winning strategy for the declarer or the defender to duck a lead — purposely refusing to win a trick when they could win it. This refers to fourth-hand play when an opponent has initiated or led to the trick.
Before you look at some examples, there is one caveat: If you duck a trick, occasionally you won’t get it, and ducking has backfired. Partners may not be understanding when this happens. Perhaps they would prefer to have “kicked the bucket” themselves, rather than go through the torture of your decision.
To avoid this, here’s my rule:
[box type=”info” style=”rounded” border=”full”]Never duck a trick unless you have a specific reason to do so.[/box]
What are those reasons?
Ducking as declarer in notrump
Let’s begin to create a “duck it” list. The most common situation occurs when you are playing a notrump contract in which the opponents have led your weak suit. Say you have 6-3 in dummy and A-8-4 in your hand. You probably know that the winning strategy is to duck two rounds of the suit and win the third. This will sever the communication between the defenders when the suit divides 5-3, usually with left-hand opponent the one who has five. If you lose a trick to RHO, he won’t be able to cash the remaining two defensive winners.
You know that, but you may not know what to do when you have two stoppers in a notrump contract such as 8-6-3 opposite A–K–5.
If the opponents lead this suit, should you duck here too?
The answer is, as is often the case, it all depends. Look at this example:
Suppose you are playing 3NT, and West leads her fourth-best diamond.
You play low from dummy and right-hand opponent plays the 
J. If you win the first diamond (an error), you are subject to a nasty guess: Which ace do you knock out first? Suppose you randomly choose hearts. RHO will win and push back a diamond. Suppose you duck that and win the third round.
Because clubs don’t split, you only have eight tricks, and when you lead a spade to develop that suit, LHO wins and takes her remaining diamonds for down one (three diamonds and two aces). If you happen to knock out the 
A first, you would survive, because when RHO later gained the lead (with the 
A), she would have no more diamonds to play.
But you can double our chances of success if you duck the first round of diamonds, and win the second. Now, even if you guess wrong and knock out the “wrong” ace (hearts) first, RHO will have no more diamonds to continue the attack. You retain your second stopper and can easily drive out the ace of spades.
The long-standing rule is:
[box type=”info” style=”rounded” border=”full”]With two key cards to knock out, duck the lead, even with a double stopper. [/box]
It’s sort of odd: Winning the first and ducking the second doesn’t quite get the job done, but ducking the first and winning the second does! Next month, some more reasons to “duck it” will be presented.
To Be Continued …