[jeffford76]

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At these colors and position 2♠ is wide ranging, and can be a 5-card suit. Partner leads the ♦J which promises the ♦Q and denies the ♦K. Now what?

[WellSpyder]

Yes, I would certainly unblock. Unless you tell me the lead cannot be from AQJ or QJ10 I would expect one of those for an honour lead (or QJ9 if the 9 weren't in dummy).

[kenrexford]

Not unblocking assumes that partner is an idiot. Who leads Queen from QJ-empty, rather than low, against 3NT when partner preempted? An idiot.

[CSGibson]

Yes unblock. Not close. Partner is not leading a 4 card suit in preference to your suit, and if partner has chosen to lead the J from QJ8xx, that is ill-considered imo, and the defense is on partner.

[jeffford76]

So obviously one should unblock if partner will "always" have QJ10.

The recent Bird opening lead book suggests that double dummy it's right in many situations to lead high from two honors only. Assume that both of you are in agreement that you don't always promise the third honor. Is it still right to unblock here?

Or, to turn the question around, if you weren't worried about partner misreading the position, would low or high from QJxxx be more likely to be the right lead?

Also, I should have specified in the OP, but this is matchpoints, which could affect things.

[cherdano]

Partner preempted in a different suit. No way I would ever lead high from QJxxx.

[CSGibson]

Unblock. Partner has to have a good reason to lead his suit instead of yours, and QJT may be sufficient. And I don't think this is one of the situations that its right to lead high from 2 honors - partner is liable to be short, and you are likely to crash one of 3 potentially helpful honors by leading high.

[akhare]

Casting my vote with the unblock bloc .

We might be headed for a 0 if declarer has AT9x or something similar, but surely pard would lead low from QJxxx?

[WellSpyder]

 jeffford76, on 2013-November-06, 17:49, said:

The recent Bird opening lead book suggests that double dummy it's right in many situations to lead high from two honors only. Assume that both of you are in agreement that you don't always promise the third honor. Is it still right to unblock here?

Or, to turn the question around, if you weren't worried about partner misreading the position, would low or high from QJxxx be more likely to be the right lead?

This hand seems like quite a good illustration of the problems of using double dummy analysis to make this sort of decision.

Or, to turn it around, I'm not convinced your second question is really the relevant one. There will be some hands where low from QJxxx works better, and others where high from QJxxx works better. But if you agree that partner cannot expect more than QJxxx then you have created a problem on the hands where you actually have QJ10xx since partner no longer knows what to do. Of course this isn't a problem for double dummy analysis since the computer will always get it right with Kx, but in real life you have just made it impossible to defend certain hands properly.

[Fluffy]

 jeffford76, on 2013-November-06, 17:49, said:

So obviously one should unblock if partner will "always" have QJ10.

The recent Bird opening lead book suggests that double dummy it's right in many situations to lead high from two honors only. Assume that both of you are in agreement that you don't always promise the third honor. Is it still right to unblock here?

Or, to turn the question around, if you weren't worried about partner misreading the position, would low or high from QJxxx be more likely to be the right lead?

Also, I should have specified in the OP, but this is matchpoints, which could affect things.

Just to make things clear: I would unblock even if partner could have led from 3 cards like !dQJx, even if he leads the queen which is consistent with Qx I will still play him for the most likely QJ10xx. Note that we could blow a trick even when he has ♦QJ10x, if that´s the case well... tough luck, blocking the suit on a normal lie out is way worse.

[jeffford76]

 WellSpyder, on 2013-November-07, 04:02, said:

This hand seems like quite a good illustration of the problems of using double dummy analysis to make this sort of decision.

Or, to turn it around, I'm not convinced your second question is really the relevant one. There will be some hands where low from QJxxx works better, and others where high from QJxxx works better. But if you agree that partner cannot expect more than QJxxx then you have created a problem on the hands where you actually have QJ10xx since partner no longer knows what to do. Of course this isn't a problem for double dummy analysis since the computer will always get it right with Kx, but in real life you have just made it impossible to defend certain hands properly.

Both choices make it impossible to defend certain hands properly. The question is which method allows more hands to be defended properly. I do understand that double dummy lets you get all of them right.

[WellSpyder]

 jeffford76, on 2013-November-07, 11:16, said:

Both choices make it impossible to defend certain hands properly. The question is which method allows more hands to be defended properly.

Fair point. If you are concerned with imps as well as mps, then it is also relevant whether the hands where you can get it right are also more likely to be the ones where there is actually a chance to get the contract off, which might just point to being able to get the QJ10 hands right rather than the QJ ones.

[jeffford76]

 WellSpyder, on 2013-November-07, 11:41, said:

If you are concerned with imps as well as mps, then it is also relevant whether the hands where you can get it right are also more likely to be the ones where there is actually a chance to get the contract off, which might just point to being able to get the QJ10 hands right rather than the QJ ones.

Agreed - I didn't think this was particularly interesting at imps. But low at matchpoints has a lot of trick blowing potential.