[kasharic]

Hi all. As a relative beginner, I'd very much appreciate your thoughts on this scenario.
It's taken from a robot IMP match. Playing the 3NT contract, I and most other tables ended up 2 off. The 4♠ was led, I played 3♠, and east won with the 8♠.
On a couple of other tables, however, I noticed the declarer played Q♠ from dummy. Even though east won with the ace, the 4♥ was returned.
My question is: is there a good reason why to play high from dummy (e.g. perhaps to give the impression that the king is held in hand) - or is this simply a play against the robot (and should not be replicated in real play)?
Thanks in advance

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[manudude03]

The answer to why people play the queen is simply because West might have led low from AKxxx meaning that the queen will win the trick if it is played immediately. The contract should go 2 down regardless.

Edit: Note that if you play small from dummy, East should play the ten. Some people do miss that part.

[kasharic]

 manudude03, on 2017-August-27, 06:26, said:

The answer to why people play the queen is simply because West might have led low from AKxxx meaning that the queen will win the trick if it is played immediately. The contract should go 2 down regardless.

Edit: Note that if you play small from dummy, East should play the ten. Some people do miss that part.

Thanks for the reply. Why would East play the ten and not the Ace? Also, isn't it safer for declarer to hold onto the queen, it keep it as a probable stopper? Ta again

[Vampyr]

 kasharic, on 2017-August-27, 07:23, said:

Thanks for the reply. Why would East play the ten and not the Ace? Also, isn't it safer for declarer to hold onto the queen, it keep it as a probable stopper? Ta again

The Queen will not be a stopper unless East is forced to win with the ace or king, so if you are not putting up the Queen at least play the 9, hoping that West led low from a suit headed by J10.

[dokoko]

Playing the Q wins when W has ♠AKxx and saves a trick when he has AKxxx. It also wins when a robot sees reason to do something stupid.
Playing the 9 wins when W has ♠AJ10x/KJ10x/J10xx (or J10xxx and E has ♣A) and saves a trick when W has AJ10xx/KJ10xx. It also wins against some weak human opponents holding AJx(x)/A10x(x)/K10x(x) in the East seat (against those playing low is even better) or against a robot doing something stupid.

You have to judge which scenario is more probable (given that West didnt lead the jack).

In the actual position your only chance is to play for RHO being an idiot, which seems to have worked at some tables.

[dokoko]

 kasharic, on 2017-August-27, 07:23, said:

Thanks for the reply. Why would East play the ten and not the Ace? Also, isn't it safer for declarer to hold onto the queen, it keep it as a probable stopper? Ta again

If you look at it from East's side, you see:

If declarer has Jx(x), he has a stopper whatever you do, so finessing against dummy won't cost.
If declarer has xx(x), he has a sure stopper if you play the ace, but won't take a trick if you finesse against dummy.
If declarer has Kx(x), he will make two tricks if you play the ace, but only one if you finesse against dummy.

Finessing against dummy can only cost if partner gets in and doesn't continue spades (which he should). So East should play the 8 (as he did) and continue with ace and another.

As a general rule: When partner leads a low card you should always consider finessing against dummy's honors (judging whether such a move is more likely to gain or to lose). But you should not finesse "against partner" (i.e. if dummy only has low cards you should play high - lower of equals when suit is headed by a sequence).