[billw55]

Partner leads the ♦4 against 3NT. Dummy holds ♦T63 and plays low. You hold ♦J85. Up with the jack? Or stick in the eight to keep the ten covered?

[jdonn]

Not enough information to answer. For example if he has Q974 you better play the 8 but if he has KQ74 you better play the jack. If he has A974 the 8 is better (but may not gain for you), whereas if he has AQ74 then the J is better (but may not gain for you).

The bottom line is there is no definitive answer here without an auction and dummy.

[billw55]

jdonn, on Mar 9 2010, 01:37 PM, said:

Not enough information to answer. For example if he has Q974 you better play the 8 but if he has KQ74 you better play the jack. If he has A974 the 8 is better (but may not gain for you), whereas if he has AQ74 then the J is better (but may not gain for you).

The bottom line is there is no definitive answer here without an auction and dummy.

I don't recall the whole hand. But the auction was 1NT-3NT and dummy is a nondescript 10 count. There weren't any relevant inferences I was aware of, it seemed like a pure 3rd hand theory question.

Yes obviously the 8 works if partner has the nine, but there's no way to know that, hence the theoretical question

[jdonn]

It would also help to know the rest of our hand. At the extremes if we have a 13 count we would rather play partner for the 9 but if we have 0 points outside this suit we will put in the jack and play him for a strong holding.

Sorry I don't think there is a right theoretical answer. Maybe in a vacuum you could just count all the holdings but that's still not clear since sometimes one card always blows a trick and other times it just sometimes blows a trick, or freezes the suit, or whatever.

[billw55]

jdonn, on Mar 9 2010, 01:46 PM, said:

Sorry I don't think there is a right theoretical answer.

OK, thanks, that by itself tells me alot.

[ONEferBRID]

If Partner has led from 4 cards, that gives Declarer 3 cards.

Let's say Declarer has K Q 9 ... it doesn't matter what you play ( J or 8 ).
Declarer always gets 2 tricks.

Since the deuce is out, partner may have led from 5 ...
Sooo, that gives Declarer only 2 cards....and they may be the A 9.... soo, you need to play the J.

[jdonn]

If you play the J and declarer has AQ2 and partner gets on lead next, he is endplayed.

If you play the J and declarer has AK2 and partner gets on lead next, he is endplayed.

If you play the J and declarer has KQ2 you simply blow a trick.

If you play the J and declarer has KQ alone you simply blow a trick.

Having thought about it all I agree the jack is more likely to be right but it's not simple...

[pooltuna]

jdonn, on Mar 9 2010, 01:37 PM, said:

Not enough information to answer. For example if he has Q974 you better play the 8 but if he has KQ74 you better play the jack. If he has A974 the 8 is better (but may not gain for you), whereas if he has AQ74 then the J is better (but may not gain for you).

The bottom line is there is no definitive answer here without an auction and dummy.

Sure there is, but not without a lead agreement. assuming 4th best leads the 8 is only rignt in 2 cases. When declarer holds specifically KQ and remains with a guess with KQ2. The J is right and the 8 wrong when declarer specifically holds A92 or the A9. The K92 holding makes the play of the 8 require you to have an entry for a ♦ lead through. Consequently the standard play is right more often.

[nigel_k]

As Josh said, the dummy and bidding matter. E.g.

A. Partner has Q9xx. The 8 is better but the J is ok as long as you gain the lead before partner does.

B. Partner has Q7xx. The J is better but, again, only if you gain the lead before partner does.

C. Partner has AQxx. The J is better, but the 8 is ok as long as you will gain the lead first.

D. Partner has KQxx. The J is better.

However, the last two will gain you three tricks in the suit if you get it right and two otherwise. If you need three tricks in the suit then just play the J, but if you only need two tricks then either card works on C and D. Of course you often can't work out at trick 1 exactly how many tricks you need from the suit. But you should have some layouts in your head and a plan to deal with them.

As a rule of thumb though, normally you would play the J in your example but play the 8 if dummy had 10x instead of 10xx.

[Fluffy]

don't like to be picky, but Q7xx is not consistent with the lead.

[pooltuna]

Fluffy, on Mar 9 2010, 07:17 PM, said:

don't like to be picky, but Q7xx is not consistent with the lead.

since we have no idea what the lead agreement is (caveat I don't remember one) 3rd best leads would be consistent with this holding as in Q742