Puzzle 8R69 Main


Unmakable Slam


 by Richard Pavlicek

Consider the following West and East hands, defending 6 NT by South.

Prospects to defeat 6 NT are bleak, as declarer must have at least 11 top tricks: five diamonds, three clubs, two hearts and one spade. Even if no other trick can be established, East is likely to be squeezed and/or endplayed in the major suits. Nevertheless, bleak does not mean hopeless; declarer may have communication problems.

Complete the deal so that 6 NT cannot be made against best defense.
A further goal is for 6 NT to be defeated by the fewest opening leads.

6 NT SouthS  ?
West leadsH  ?
D  ?
C  ?
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S  ?
H  ?
D  ?
C  ?

Before reading further, see if you can pick the N-S hands of the best solution:

S A J 10 8
H 4 3 2
D 5 4 3 2
C 9 8

S
H A K J
D A K Q 10 8 6
C A K Q 10
S
H A K 4 3 2
D 10 8 5 4 3
C K 10 9

S A J 10 8
H J
D A K Q 6 2
C A Q 8
S 10 8
H 4 3 2
D 10 8 6 5 4 3 2
C Q

S A J
H A K J
D A K Q
C A K 10 9 8
 S A 10 8
H 4 2
D 10 8 6 5 4 3 2
C 10

S J
H A K J 3
D A K Q
C A K Q 9 8
 S A J 10 8
H
D 8 3 2
C A K Q 10 9 8

S
H A K J 4 3 2
D A K Q 10 6 5 4
C
 S A
H J
D 10 8 6 5 4 3 2
C Q 10 9 8

S J 10 8
H A K 4 3 2
D A K Q
C A K

Puzzle 8R69 MainTop Unmakable Slam

Chang Lu Wins

For the month of May 2025, these problems were presented as a contest with 20 participants from 17 different locations. Thanks to all who entered, and congratulations to Chang Lu (China) who was the only solver to find the optimal solution.* This is Chang’s first participation in any of my contests, so one for one is quite a start. Alas, now he has nowhere to go but down.

*Contestants had to construct their own solutions. Multiple choice was only added for this writeup.

Given the West and East hands, the object was to complete the deal so that South could not make 6 NT against best defense, and with the fewest opening leads that beat the slam. Listed below are the solvers who succeeded with eight leads or fewer (next best was all 13 leads). Ties are broken by the most HCP for South.

Winner List
RankNameLocationLeads BeatSouth HCP
1Chang LuChina121
2Nicholas GreerEngland217
3Craig BiddlePennsylvania326
4Charles BlairIllinois321
5Jim MundayNew Mexico429
6Richard SteinWashington527
7Brad TheurerMaryland514
8Prahalad RajkumarIndia831

Puzzle 8R69 MainTop Unmakable Slam

Solutions

Eight at the gate

This first construction gave South every possible HCP, but any of eight opening leads defeat the contract:

6 NT SouthS 10 8
West leadsH 4 3 2
D 8 6 5 4 3 2
C 9 8
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S A J
H A K J
8 leads beatD A K Q 10
31 hcp SouthC A K Q 10

Prahalad Rajkumar: A non-club lead beats 6 NT. On a club lead, East is caught in a strip squeeze.

Five come alive

Cutting the goal to five successful leads was this solution with a deadly spade lead:

6 NT SouthS A 10 8
West leadsH 4 2
D 10 8 6 5 4 3 2
C 10
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S J
H A K J 3
5 leads beatD A K Q
27 hcp SouthC A K Q 9 8

Richard Stein: A spade lead kills the entry to the diamonds and results in down two. Any other lead allows an overtrick.

Four wheel drive

The next entry reduced the goal a notch, as only the club spots do the job:

6 NT SouthS 10 8
West leadsH 4 3 2
D 10 8 6 5 4 3 2
C Q
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S A J
H A K J
4 leads beatD A K Q
29 hcp SouthC A K 10 9 8

Jim Munday: …This deal has four successful leads (low clubs). The C J allows for five club tricks and an endplay (or heart hook).

Three point landing

Going one better was this solution, which locks declarer in hand with a diamond lead:

6 NT SouthS A J 10 8
West leadsH 4 3 2
D 5 4 3 2
C 9 8
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S
H A K J
3 leads beatD A K Q 10 8 6
26 hcp SouthC A K Q 10

Craig Biddle: Only a diamond lead beats 6 NT.

Two for the show

Capitalizing on which diamond, the next construction lowered the bar to just two leads:

6 NT SouthS A J 10 8
West leadsH
D 8 3 2
C A K Q 10 9 8
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S
H A K J 4 3 2
2 leads beatD A K Q 10 6 5 4
17 hcp SouthC

Nicholas Greer: West has to lead either the D J or D 9 to prevent access to dummy’s black-suit tricks. If declarer sacrifices a diamond trick to force a [dummy entry], there is no way back to the long diamonds afterwards and not enough tricks without them.

One for the money

This solver hit the jackpot, using clever means to discover my one-lead solution. Well done!

6 NT SouthS
West leadsH A K 4 3 2
D 10 8 6 5 3
C K 10 9
S 9 7 6 5 4TableS K Q 3 2
HH Q 10 9 8 7 6 5
D J 9 7D
C J 7 6 5 4C 3 2
S A J 10 8
H J
1 lead beatsD A K Q 4 2
21 hcp SouthC A Q 8

Chang Lu: Only one lead defeats 6 NT. This is optimal via exhaustive computer search; there are similar solutions that vary by diamond holdings, but all are D A-K-Q-x-x.

So what is the killing lead? Obviously any spade lead gives the contract, so suppose West leads the D 7, won cheaply in North. Declarer next wins two top diamonds (unblocking D 6-5) then three clubs ending in North to reach this position:

NT win 6/7STrickLead2nd3rd4th
North leadsH A K 4 3 27. ND 3!?
D 10 3
C
S 9 7 6 5 4 TableS K Q 3
HH Q 10 9 8
DD
C J 7C
S A J 10 8
H J
D Q 4
C

The D 3 lead effects a seesaw squeeze* against East. If he pitches a spade, South wins cheaply with the D 4 to establish spades with the D Q entry. If East pitches a heart, South hops with the D Q to establish hearts with the D 10 entry to North. A similar ending is reached if West starts with the D 9 or D J, so a diamond opening lead does not beat the contract.

*also called an entry-shifting squeeze

Suppose West leads a club, won by North’s 10. Declarer cashes all five diamonds ending in North to reach this position:

NT win 6/7STrickLead2nd3rd4th
North leadsH A K 4 3 27. NC 9!?
D
C K 9
S 9 7 6 5 TableS K Q 3
HH Q 10 9 8
DD
C J 7 6C
S A J 10 8
H J
D
C A Q

The C 9 lead effects the same seesaw! South wins high or low according to East’s discard, then establishes the major East shortened.

So how then can 6 NT be defeated? Remarkably, the seesaw is foiled if West leads the club jack. No matter which honor declarer wins, he cannot reach the required matrix of South holding the highest and third highest club, and North the second highest club.

Also note there is no seesaw position in diamonds without a diamond lead from West. Declarer must win D A-K-Q to capture all of West’s diamonds, leaving South with D 4-2, which cannot provide two entries. Curiously, if South held D A-K-Q-5-3, the matrix could be achieved with D 4-2 opposite D 5-3, but then 6 NT would be makable with any lead.

Seesaw recall

The seesaw squeeze, while rare in any guise, is more common at trump contracts (or Trump tariffs for that matter, which seesaw at The Donald’s every whim). A curious difference is that a seesaw at a trump contract usually wins all the remaining tricks, but at notrump this is virtually impossible. Note the qualifier, “virtually.” Eleven years ago I discovered a rare exception, inspiring my Seesaw Recall puzzle, which only one person solved. Congrats again to Leigh Matheson (Australia).

I’m getting dizzy, so I’ll hop off the seesaw and yield the floor:

Prahalad Rajkumar: If points could win contracts, this would be a slam dunk. Instead, it’s an example of South striking out.

Jim Munday: I just hope a heart lead isn’t required.

Charles Blair: The opening-lead tiebreaker must be very important. Hi-ho, hi-ho!

Charles was on to the seesaw squeeze (per another comment) but Snow White must have sent him off to work on something else.

The Donald: My advisers inform me of your continual defamation, so I have acted accordingly. You are hereby subpoenaed to appear at Broward County Courthouse, 10:00 am, June 9, 2025, re Libel Case #250520DTRP.

Your “advisers?” Would they be Huey, Dewey and Louie? And how can I defame you when public opinion has already run the gamut? To make amends I will offer these kind words: Have a safe, pleasant trip back to Lilliput! (I need the inspiration for another bridge puzzle.)

Puzzle 8R69 MainTop Unmakable Slam

© 2025 Richard Pavlicek