[SimonFa]

You are in 5♦with lefty having opened 1♠ (could be 4-card major as playing Acol) and received no support from partner.

Opening lead is the expected A♠, presumably from AK and dummy goes down:

♠J9x

♠QTx

You suspect that RHO has a doubleton so what's the best (legal) approach to try to deceive lefty and make her switch?

In practice I played T and then Q on the king continuation and lefty did switch, much to the annoyance of her partner who argued there could have been a trump promotion even if t was a doubleton. In practice trumps were solid.

I got lucky, but was this the best approach or should I have tried something other combination.

Thanks in advance,

Simon

PS FWIW MPs and can't remember vulnerability

[mich-b]

Usually the best deceptive play is the Q from hand, because LHO may worry that if he tries to cash the King , you will ruff and use the established ♠J to discard a loser. That may be true (depending on the exact spot cards) even if RHO correctly signals his count , because LHO will know that his partner has an even number of cards , but may not know if that number is 2 or 4.

Your play of Q , then 10 , will not usually work, because LHO having already established the J in dummy, will very rarely benefit from switching (only when RHO has an ace, and declarer needs one discard only), even if for some reason your opps were not able to show their count correctly.

[1eyedjack]

As mich-b says, Q is best here, although the bidding will frequently suggest that you are unlikely to be singleton. When you follow with the Ten it telegrahs your intent to try to induce a switch, and if anything will encourage a third round continuation.

The normal rule is to make the same signal that you want the leader to think that his partner is making. That would not apply in this situation, but generally, if you want the leader to think that his partner has played a high card, then you play the lowest card higher than the one played by RHO. If you want the leader to think that his partner has played his lowest card then you also play your lowest card. There are no guarantees, but it tends to be a policy that gives the leader the most (creditble) losing options.

I have mixed sympathy for the comments made by the leader's partner in this case. Once your card as declarer on the first trick has failed to elicit a trick 2 switch, any ruse is pretty much rumbled, as the opening leader's partner will have, by the completion of the second trick, removed any ambiguity from the signal that might have been inherent in the first card played. Thus, her comment is accurate that the leader should by now have enough information to continue the suit, provided of course that she has signalled intelligently and not left it up to leader's sight of declarer's cards to determine the continuing strategy.

That said, her comment about the potential for a trump promotion seems off-base. She seems to accept that from your perspective there was a possibility of declarer holding a doubleton. However, if that were the case, the thirteenth Spade would then be in her own hand so that she would not have been able to ruff the third round high so as to induce a trump promotion by the imagined overruff.

[shintaro]

1eyedjack, on 2011-July-14, 07:00, said:

As mich-b says, Q is best here, although the bidding will frequently suggest that you are unlikely to be singleton. When you follow with the Ten it telegrahs your intent to try to induce a switch, and if anything will encourage a third round continuation.

The normal rule is to make the same signal that you want the leader to think that his partner is making. That would not apply in this situation, but generally, if you want the leader to think that his partner has played a high card, then you play the lowest card higher than the one played by RHO. If you want the leader to think that his partner has played his lowest card then you also play your lowest card. There are no guarantees, but it tends to be a policy that gives the leader the most (creditble) losing options.

I have mixed sympathy for the comments made by the leader's partner in this case. Once your card as declarer on the first trick has failed to elicit a trick 2 switch, any ruse is pretty much rumbled, as the opening leader's partner will have, by the completion of the second trick, removed any ambiguity from the signal that might have been inherent in the first card played. Thus, her comment is accurate that the leader should by now have enough information to continue the suit, provided of course that she has signalled intelligently and not left it up to leader's sight of declarer's cards to determine the continuing strategy.

That said, her comment about the potential for a trump promotion seems off-base. She seems to accept that from your perspective there was a possibility of declarer holding a doubleton. However, if that were the case, the thirteenth Spade would then be in her own hand so that she would not have been able to ruff the third round high so as to induce a trump promotion by the imagined overruff.

As both the above the Queen cannot cost and should get them to switch fearing setting up Jack

[Free]

The trick is to convince LHO not to play ♠K, so his partner can't show a doubleton. Only by playing the Q you can convince LHO not to continue with a high ♠, because you might ruff and dummy's ♠J would be high.

Here you got lucky because LHO didn't believe his partner's count signal.