Suit Preference When Returning Partner's Lead in NT

In 2nd seat, all red, You hold:
T865
K9
AQT4
986



Auction:
1C (strong) - P - 1D (0-7) - P;
P - 1S - 2H (5-7, 5+H) - P;
2NT - P - P - P
Opening lead: D4



Dummy:
Q2
QJ753
532
JT5



Partner wins K and returns 9, covered with the J. You cash the Q and T. Dummy sheds a club. Partner follows with 8 and 6. Declarer pitches S7 and HT. Your lead to trick 5. What are your thoughts? For the 2NT rebid, we can expect declarer to have 16-17 (maybe 18) hcp, leaving partner with 4-6 in the remaining three suits.


Partner is up to something here by not returning fourth best. Normally the only reason for not returning 4th best is if he needs to remain on lead for a finesse through declarer or to unblock, and neither is the case with declarer known to have a doubleton diamond. So partner must be trying to show some suit preference. Does playing to-down in diamonds suggest a spade or a heart? I think it suggests hearts because spade tricks are clearly not going away and hearts aren't running. If declarer has AKJ and AK in the black suits, he has 9 tricks as soon as he gains the lead. If declarer has the heart ace, it's now stiff so it can't hurt to lead a low heart. The HT discard is very telling. It kind of gives away the position. Either he had blanked the A and is banking on a (winning) black suit finesse instead of a heart finesse to make his contract, probably with an overtrick or he just has a stiff T and has 9 black suit winners.




But what if this guy is being a hand hog and actually has three hearts and was just trying to entice you into leading from the K with a hand like AKJxx, ATx, Jx, Axx instead of attacking his vulnerable club suit? with that hand, a heart ensures the contract while a club lead could set 2NT. But if that's the case, he can have the good board and we'll chalk it up to a fix.




This play is more difficult if declarer keeps the HT and instead throws a low black card on the fourth diamond. When partner has the heart ace, it's still likely declarer will get 8 tricks if you don't take both hearts now, but he would have to be 5-5 in the blacks for it to matter. How much should we cater to declarer not bidding 3C on a 5-5 hand? I don't know - we would have to know the player's tendencies a little more. Anyway, we are back to the question of what partner's diamond plays suggest about what to do next.  We know that the heart suit isn't a threat But from partner's perspective, declarer could have xxxxx, AK, Jx, AKQx in which case a spade lead is very crucial. I suppose partner could play the 8 at trick to suggest hearts, but three-suited suit preference situations can be confusing. I'm gonna go with: in this context, spades is the suit to avoid so for partner to show a heart preference, he would lead back 4th-top-bottom (6-9-8) and to show a club pref he would lead back 4th-bottom-top (6-8-9), leading back not 4th best in this non-unblocking situation and then showing 4 suggests something else, in this case a spade. If dummy's hearts were better, I'd say hearts would be the unexpected suit and the normal suit pref signal would be between spades and clubs.



As it turned out, declarer's hand was AKJxx, T, Jx, AKQxx and the trick 5 play of a heart would lead to -1, anything else making 3. It didn't make any difference in the matchpoints because the field was either making 4S or going down 2 in 3NT.