Third Hand High
When the lead is made, and neither your partner (who has led), nor dummy, has won the trick, and you're the third person to play, you need to play as high as possible, because it's your side's last opportunity to win the trick. This is known as "third hand high". Your high card may promote a winner in partner’s hand, even though it doesn't win the first trick. That's fine, but don’t let declarer win a cheap trick. This applies to subsequent tricks, not just the first one.
The card you choose depends on: the cards you hold in the suit led, what particular card partner led, and the second card played to the trick (dummy).
Play only as high a card as is necessary to win the trick. With a choice of touching cards, play the cheapest one, e.g. you hold the ♠QJ10 and partner leads low, dummy plays low, and you're next. Play the ♠10, not the ♠J or the ♠Q. If that forces a higher card from declarer, at least partner will have an idea you hold the ♠J and the ♠Q when the ♠10 forces the ♠K or the ♠A.
Sometimes you must unblock a suit by overtaking partner’s card, when you have a doubleton honour. e.g. partner leads the ♠K and you hold the ♠A4. Play the ♠A on top of the ♠K and return your ♠4. If you don't play the ♠A you will have to win the next trick with it, and won't have a spade to return to partner's long and high spades.
When deciding how high to play, try to keep the opponents’ high cards trapped if possible. If the second hand has a high card which isn’t played, and you have both a higher card and a lower card which might win the trick, play the lower card. e.g. parter leads the ♠4, dummy holds the ♠K1096, and you hold the ♠AJ85. If dummy plays the ♠10, you should play the ♠J not the ♠A. Even if declarer's ♠Q wins the first trick, you have kept your cards sitting over dummy's. If partner had led from the ♠Q, then your ♠J will win.
It's much easier making sense of these carding situations if you play hands and go through them afterwards, than it is reading about it! The one thing people shouldn't do is make up their mind which card they intend to play to a trick, regardless of which card declarer or dummy plays. You might have been able to win the trick more cheaply than you expected, but sometimes players have made up their minds, and play that card too quickly!
Test your knowledge
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