It is interesting being a defender and facing the best line of declarer play. This problem was inspired by one of the Bridge Master hands, where we know we always have to take the best possible line as declarer in order to complete a level. 

But how about if you defend against one such declarer? 

You are East and hold this hand. 

Your opponents are using a simple natural system where the 2 Clubs response shows 4+ clubs and 6-8 HCP and 3 NT shows a 18-19 HPC balanced hand.

The lead is Q of spades by your partner and you see dummy:

While declarer is thinking, you quickly see that if he has a minimum of 18 points, your partner should have at most 5-6 points. 

As he has shown the QJ of spades with the lead, there is no chance of him having an ace as well. 

If he has the K of hearts, declarer has no chance of making 9 tricks as you will always escape any attempt of end play. 

If he has doubleton King or Queen of clubs still we see that club finesse is working, or if the Queen is a problem there is a small chance of declarer missguessing it. Not a great possibility. 

But we see, we hope … that declarer is thinking, and we know he is a good player especially as declarer. We have to try and guess what his thinking is. 

He wins the second round of spades (your partner continued with the Jack) and suddenly, instead of starting clubs, he starts with Diamond Ace. 

What is happening ???? Time to think very fast. 

We can picture him with a hand like: 

or

For sure he is afraid of missguessing clubs or club finesse not working. As a good declarer, he has found that he will be increasing his chances if there is a miracle in diamonds, like the singleton diamond King falling! Small chance, but possible, and then he will be able to make 5 diamonds by finessing your partner, plus 1 spade, 2 hearts and only one club (or 2 if he has the king). He can then make his contract avoiding the guess in clubs. If there is no miracle in diamonds, he will have to guess the clubs but playing on diamonds first is giving himself an additional chance. 

Now is the time to shine! Drop the King of diamonds, give him the much needed miracle! Then, after taking the “marked” diamond finesse you will win with the diamond Jack and enjoy your long spades for down one. 

Of course, a good declarer, aware that he has a good opponent, will try to guess how you are thinking and perhaps smell the trap… This is how interesting our game is, and what pleasure you can have playing it.