An unblocking play by the defense is the intentional play of an unusually high card to maintain communication with partner. For example:
| | Dummy | | |
| ♣ J 3 | |
| West | | East |
| ♣ A K 10 9 8 | | ♣ Q 7 6 |
| Declarer | |
| ♣ 5 4 2 | |
West leads the top two clubs. East can theoretically unblock the
♣ Q, which would allow West to run the suit.
Unblocking vs. Overtaking
Unblocking is similar to the act of overtaking partner's lead or winner. The difference is that the latter always involves following suit with a higher card than partner's. Consider this suit distribution:
| | Dummy | | |
| ♣ A 3 2 | |
| West | | East |
| ♣ Q J 10 9 8 | | ♣ K 7 |
| Declarer | |
| ♣ 6 5 4 | |
West leads the
♣ Q, ducked in dummy. East can choose to overtake with the
♣ K and return the suit, which would let West drive out dummy's ace. But if East plays low to the first round and West continues the suit, declarer can duck a second time to preserve dummy's ace.
Unblocking on the opening lead vs. no-trumps
There is one conventional opening lead against no-trumps that demands an unblocking play from partner:
| | North | | |
| ♠ A 4 3 | |
| West | | East |
| ♠ K Q 10 9 6 | | ♠ J 5 |
| South | |
| ♠ 8 7 2 | |
West leads the queen from a suit headed by the
K Q 10 9. This is a standard lead that asks East to drop the jack regardless of whether declarer ducks the trick. Upon seeing the
♠ J, West will know that the defense is entitled to four spade tricks.
What if this was the distribution instead?
| | North | | |
| ♠ A 4 3 | |
| West | | East |
| ♠ K Q 10 9 6 | | ♠ 8 5 |
| South | |
| ♠ J 7 2 | |
East should give count on the first trick by playing the
♠ 8. If declarer ducks, West should recognize the danger of continuing the suit since partner failed to unblock.
Example
An unblocking play can also arise when declarer is on lead.
| | North | | |
| ♠ J 9 7 6 | |
| ♥ 5 4 | |
| West | ♦ A K 5 | East |
| ♠ 5 4 | ♣ A J 8 3 | ♠ 3 2 |
| ♥ A K | | ♥ Q J 10 9 8 7 |
| ♦ J 10 9 8 | South | ♦ Q 6 2 |
| ♣ 9 7 5 4 2 | ♠ A K Q 10 8 | ♣ K 6 |
| ♥ 6 3 2 | |
| ♦ 7 4 3 | |
| ♣ Q 10 | |
West
Pass
Pass
|
|
North
1 ♣
2 ♠
4 ♠
|
|
East
Pass
Pass
All Pass
|
|
South
1 ♠
3 ♠
|
West leads the
♥ A and East indicates his sequence by playing the
♥ Q. When West continues with the
♥ K, East follows with the
♥ 7. This should be suit-preference for the lower of the remaining side suits — clubs. However, West has difficulty interpreting the medium spot card and switches to the
♦ J.
Declarer wins the
♦ A and draws two rounds of trumps, ending in her hand. She then ruffs a heart in dummy while West discards a club. The position becomes:
| | North | | |
| ♠ J | |
| ♥ — | |
| West | ♦ K 5 | East |
| ♠ — | ♣ A J 8 3 | ♠ — |
| ♥ — | | ♥ J 10 9 |
| ♦ 10 9 8 | South | ♦ Q 6 |
| ♣ 9 7 5 4 | ♠ Q 10 8 | ♣ K 6 |
| ♥ — | |
| ♦ 7 4 | |
| ♣ Q 10 | |
South proceeds to cash the ♦ K. East must be careful to unblock the ♦ Q — otherwise, he'll be thrown in with a third round of diamonds. At that point a heart return would give South a ruff-and-sluff, while a club return would be equally fateful.
