In this symmetric deal, nine tricks can be made in notrump by any declarer.
Given the symmetry of the deal, we only need to analyze one declarer, so we pick south as declarer just for consistency.
Fundamentally, the problem for the defense is that even though they can set up either diamonds or clubs with one lead of the suit, the suits are blocked, and there is no immediate entry to the suit that is set up.
Isn't declarer similarly blocked? Yes. But look what happens to
the deal when west leads a low club. North pitches a spade,
and south wins the trick in his hand, then leads a low spade to the ten,
east winning the jack, leading to:
But what if west leads a diamond? Then north covers, and, whatever east does, south pitches a heart. Now, south only needs to lose one heart to take seven heart tricks, plus a diamond and a spade.
Finally, if west leads a heart, he lets east pitch a club to begin
an unblock, but he does nothing to set up any of his own suits.
Instead, he has blown his heart stop. Declarer just wins three
hearts and plays a low spade to the ten, and east is forced to win,
leading to this position:
Each side has two suits they might try
to set up. In order to set up and run a suit, they need to lose a
trick in the suit, and then either pitch a card from the
Now, when west leads a club, he does the first step - losing the
mandatory club trick. But the club also lets north pitch a spade, so
both sides take a step towards their respective goals. When north leads
a spade to lose to east, west gets to pitch, but he holds the
I have computed double-dummy results for about 930,000 symmetric deals out of 16,777,216 different symmetric deals, systematically choosing good "representatives." [Basically, if you have a symmetric deal, you can get to one of my representatives by swapping around spots smaller than the eight. ]
Of these deals, this is the only one where each side can make nine tricks. In fact, it is the only one that can make more than seven tricks. Is this deal unique? I can't claim that at this moment, but I would not be surprised if it was.