[AL78]

In the interest of not looking like I am deliberately posting hands where my partner made a mistake, here is one where I just didn't think at trick 2. Cross-IMPS.

South
♠74
♥AJ9832
♦74
♣Q87

---

2♦ was the Multi.

Partner leads the ♥7. Dummy comes down with:

♠AK2
♥K54
♦T63
♣A94

Declarer plays the 6. What do you do after winning with the ace?

You would likely deduce the heart is a certain singleton and return one for partner to ruff, who would then cash two top diamonds taking the contract down. I had the fact she bid diamonds at the three level stuck in my mind, thinking if declarer held the king I need to lead through it now or never, and returned a diamond without thinking, blowing the defence.

---

I must make a plan before playing to trick 2.
I must make a plan before playing to trick 2.
I must make a plan before playing to trick 2.
...

Not as bad as it could have been (only four tables, and one pair went three off in 2♥, no-one else bidding game EW), but still, if it is an evening where we have to defend 15 out of 21 boards, I really need to do better than this.

[Cyberyeti]

Which is why declarer should play the ♥10 under the ace, leaving the possibility that partner has a doubleton.

[LBengtsson]

your fault, partner fault also. she should lead ♦A, see your card before leading stiff ♥ at trick two or three. leading ♥ trick one says that she do not have ♦AK, maybe ♦AQ. defense takes two to tango. declarer can false card trick on ♥ lead and you do not if partner has ♥x or xx as cyberyeti says.

[apollo1201]

Where I live, it is almost standard when having AK and a side singleton to lead K then switch. Like this, partner could have made you impossible to go wrong...

[AL78]

 apollo1201, on 2021-March-13, 14:09, said:

Where I live, it is almost standard when having AK and a side singleton to lead K then switch. Like this, partner could have made you impossible to go wrong...

That may be true, but I still should have thought about it more instead of playing too quickly. I know that in some cases, it is possible to guide partner to the correct action, but that is no substitute for working things out.

[pescetom]

 AL78, on 2021-March-13, 15:17, said:

That may be true, but I still should have thought about it more instead of playing too quickly. I know that in some cases, it is possible to guide partner to the correct action, but that is no substitute for working things out.

I agree with the others, partner had a clear bid of either ♦A or ♦K according to agreements.
So you're still deliberately posting hands where partner made a mistake

[AL78]

 pescetom, on 2021-March-14, 15:25, said:

I agree with the others, partner had a clear bid of either ♦A or ♦K according to agreements.
So you're still deliberately posting hands where partner made a mistake

As a result of the surprising responses, I am going to discuss this situation with her because we don't (as far as I know) have any agreement that leading an ace or king from an AK combination then switching says "give me a ruff". With a different (my more regular) partner, I once did lead an ace then switched to a singleton, which she won, then didn't return the suit. Her reasoning was if it was a singleton, I would have led it at trick one.

[smerriman]

 AL78, on 2021-March-14, 17:07, said:

.. that leading an ace or king from an AK combination then switching says "give me a ruff"..

I wouldn't say that at all; it's more the reverse implication - leading something else almost always denies having an AK, since that's the #1 choice of lead in almost all situations.

[apollo1201]

 AL78, on 2021-March-14, 17:07, said:

As a result of the surprising responses, I am going to discuss this situation with her because we don't (as far as I know) have any agreement that leading an ace or king from an AK combination then switching says "give me a ruff". With a different (my more regular) partner, I once did lead an ace then switched to a singleton, which she won, then didn't return the suit. Her reasoning was if it was a singleton, I would have led it at trick one.

While it can be quite common to switch after leading an A from AK (see dummy, partner’s signal or count...), imagining that the switch is a sg is impossible.
However, leading K then switching is a clearer signal (unless the switch can be legitimately linked to other reasons, sg in dummy, partner thinking a Bath Coup is around...). In that case, it is less legible that you have a sg.

[AL78]

 apollo1201, on 2021-March-16, 01:04, said:

While it can be quite common to switch after leading an A from AK (see dummy, partner’s signal or count...), imagining that the switch is a sg is impossible.
However, leading K then switching is a clearer signal (unless the switch can be legitimately linked to other reasons, sg in dummy, partner thinking a Bath Coup is around...). In that case, it is less legible that you have a sg.

Thanks, smerriman explained it clearly, leading A or K strongly implies holding touching honors (and vice versa), so if partner leads an ace followed by a likely singleton, it is easier to decide to give a ruff.