Source: http://www.andrewrobson.co.uk/
This is a “Trump Coup”:
 – 2 2 - |
|
| K J – – – |
|
| A Q - – – |
With the lead in hand, you cannot avoid losing to East’s K. In dummy, however, the lead of either card “coups” East’s trumps (you cover cheaply). It did not matter that you were not leading a trump from dummy. Effectively, this is your only way to pick up a finesseable trump holding on your right, with no further trumps in dummy.
In order to reach the desired ending, you must have the same number of trumps as East, and this usually entails reducing your trumps earlier. Take this grand slam deal.
- 3 NT is possible, with diamonds well stopped. However South has announced a self-supporting spade suit.
- How many aces? Answer: two.
- How many kings? Answer: one.
- Can count 13 tricks (assuming no trump losers) if North’s king is K; 12 if it is K.
Contract: 7 by South
What happened
Declarer won Q lead with K, and cashed AK. Crestfallen to see the 4-1 split seemingly wreck his good grand slam, he could not see a way to avoid losing to East’s J. He cashed Q and conceded to East’s J. Down one.
What should have happened
Because he has no more trumps in dummy with which to lead through East, he needs a Trump Coup. This involves reducing his trump length to the same as East. Three ruffs are required.
After winning K and cashing AK, you cross to A and ruff a heart. Cash A, cross to J and ruff a third heart. Cross to K and ruff a fourth heart. Finally cross to A and lead either card. You have Q10 sitting over East’s J9, and his trumps are “couped”. 13 tricks and grand slam made.
If you remember one thing…
When dummy has no trumps left to finesse against an opposing honour, you can use Trump Coup technique. Condition: you must have the same trump length.