More often than not I keep illustrating defensive problems because defence is the most difficult part of bridge and quite often we see even the best slip in defence much to the delight of the dejected declarer who had almost given up hope of making his bid contract.
Slips in defence keep cropping up and shall be an on going process because as we know bridge is prone to human vulnerability and therefore errors, will be made on both sides of the fence. It is only in the cutting down of errors and improving with each error and also not repeating the error that we tend to become better bridge players.
While a lot of us pay attention to the more significant aspects of bridge defence like standard signals, opening leads, counter defensive strategies, count signals, suit preference shifts, lock in and end play techniques with a host of other defensive measures to make the declarer as uncomfortable as possible, we sometimes fail to keep a vigil on each and every move of partner, slipping in our concentration especially when it comes to what seems to be irrelevant discards, little realising that what seemed so irrelevant and insignificant to us could be the very life sustaining signal for the defence as was done on our present illustration of defence. See if you can spot the signal and understand its implications in the overall context of the game, with the declarer being in a contract of a grand slam of 7NT bid as under:
The opening lead was 10S, taken in dummy with the queen, declarer following with the 6S. A word about the bidding: 2NT showed 20-21 HCP with balanced hand, 4C was Gerber ace asking and 4NT showed three aces.
We will place you in the south seat for today's defence of the grand slam with the dummy exposed on your right, which was east's hand as under along with your holding.
Although your holding as south consist of only the lone jack of spades with a flat, pictureless distribution involving in you very little enthusiasm or excitement in defending 7NT, which is human nature as you tend to lose interest seeing little hope in your contribution and pinning not too much hope either partner for as you can see a very strong dummy exposed on your right holding 15 HCP, which with declarer's opening 2NT of 20-21 HCP, which give the opponents the almost ideal point count of 35-36, if not the ideal 37 HCP requirement for the GS.
The declarer takes a long time to plan his play on trick one. He puts in the QS, which holds and goes in a deep trance again before playing a heart to the ace, a heart to the jack in hand and again back at heart the king in dummy. All three hearts fill up 12 cards and now the declarer play his 13th card the heart queen with partner discarding 2, 5, and the dummy a low club and suddenly you find yourself in the spotlight. Your discard may or may not become the factor in the making or breaking of the contract. But it can illuminate your partner with the knowledge of your distribution that could turn out to be vital for him and vice versa.
Now, as in all defence discards by now you must have conjured up the declarer's possible hand with count of HCP and distribution of suits. Let us see what possible holding declarer could have. Let us take the spade suit first. What do you place partner in spades on his 10S lead followed by his discard of the 2S. By the way, do you remember what was your spade signal of the opening lead from partner of the 10S. Well it must and should be an encouraging 7S, which would cater as a come on signal.
Looking at the fact that declarer in clubs could hold AQJ (7 points) with AKQ hearts shown, (9) totalling 16 points, diamond jack (1) it gives a margin of only 4 or 3 points in spades either ace or king. The king being impossible in a 6S contract leaves a margin of the ace. But with KS, would partner lead 10S followed by 2S - another improbability. This brings us to the conclusion that declarer must hold AK of spades, which added to his AKQX of hearts give him 16 HCP along with the AC shown by his 3 ace showing response making up the 20 HCPs. If he holds the JD too, which he can, then his tricks count is 2 in spades, 4 in hearts, 4 in diamonds and 2 in clubs making up the 13 tricks and giving you no hope whatsoever. So you must presume he is missing the JD to give you any hope. Obviously your partner's JD is falling. Therefore, your fourth diamond becomes a vital trick taking card - 8D over dummy's 7D. But only one uncertainty still prevails. What if declarer holds 4 card spade headed by the AK with your partner holding 1092. Then a spade discard from you can spell curtains for the defence. It is here that we should learn the "current count" defence signal. Once your 7S signal showed encouragement partner can show "current count" ie with 3 spades originally he would discard the 9S from holding of 109X. But with 10982, after 10 is played, the current holding becomes 982 and the 2S shows 3 card holding making it mandatory for you to hold to your diamonds knowing declarer cannot have more than 3 cards in spades.

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The bidding:
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West     North     East      South
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2NT         P        4C          P
4NT         P       7NT   ALL PASS
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 East     South
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   Q5      J743
  J42      1053
 AKQ7      8542
K1032        75
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