Which suit do you attack?

Playing at the local duplicate, I was dealt ♠KT854 ♥9 ♦QJT6 ♣KQ4 in fourth seat, fav vul.  LHO opened 1♣, partner overcalled 1♥, and RHO passed.

What is your call?  In this partnership, 1♠ would be “nonforcing constructive”.  Rightly or wrongly, I judged that my lack of heart fit caused my hand to fall somewhat short of “constructive” and so chose to respond 1NT.  That closed the bidding and a fourth best ♣5 was led.

North ♠ KT854 ♥ 9 ♦ QJT6 ♣ KQ4

South ♠ 732 ♥ AQ876 ♦ A74 ♣ J2

North is the declarer at 1NT, with East having led a fourth best ♣5, likely from a five card suit.

One of the better playing tips I have read is one from Danny Kleinman: when playing a notrump contract, consider going after the suit that will produce the most incremental tricks, even if not your longest suit.  Here, the diamonds have only one top winner, but three diamond tricks can be easily taken if that suit is attacked, an increment of two tricks.  The spades are longer, but the number of tricks to be developed in spades is murky, especially since the ♠A is likely to be with East, the opening bidder.  Thinking along the lines suggested, I decided to attack diamonds.

The best play for four diamond tricks, of course, is to win the club in hand (North) and take a diamond finesse, hoping to find East with Kxx.  However, I could envisage a couple of problems with that approach:

• If East plays the ♦K from Kxx on the third round of the suit, the diamond suit is blocked.  Having won the first club in my hand, the defenders might be able to keep me from having a quick entry to the fourth diamond.  Should West gain the lead, a club through North can be ducked to dummy’s jack.
• If West owns the ♦K, she can duck the first diamond finesse and win the second diamond finesse, again blocking the diamond suit.  A club back again keeps me from having a quick entry to my hand.

The diamond blockage and the lack of quick entries to my hand seemed to be serious issues to me.  Accordingly, I played the ♣J from dummy (South) at trick one, winning the trick, and continued with ♦A and a small diamond to the ♦Q.  Both opponents followed suit and the ♦Q was allowed to win the trick.  With two diamonds in the bag, how should I continue?

At this point, the number of incremental tricks from continuing diamonds is only one: I have two diamond tricks and can build one more winner by playing a third diamond, no more and no fewer.  Do spades now represent a better chance to build incremental tricks?

If East owns ♠A in a doubleton holding, I can play two small spades from my hand, make the ♠A fall on air and produce three slow spade tricks.  That was my thinking (?) anyway, as I next led a small spade away from my five card holding.  East played the ♠9, West the ♠6.  East continued the ♣A and the ♣3, West following to both tricks as I pitched a heart from dummy on the third club, winning in my hand.

Still hoping for East to have owned the ♠A9 doubleton, I continued with a second small spade.  East played the jack and West discarded a high heart spot.  Oops, East had been dealt AQJ9 of spades!  East cashed out her last two clubs as West completed a heart echo and then played a third heart.  Perhaps East should now play a heart, but at the table, she, having already won three clubs and two spades, proceeded to cash the setting tricks of the ♦K and the ♠A before I could claim.  Down one, in a contract I bet I could have made had I continued a third diamond when I chose to switch to spades.

In retrospect, I think that continuing diamonds would have been a better play.  I was always going to lose at least three clubs and two spades (assuming the ♠A is offside).  I would have to have been quite fortunate, and perhaps benefited from a misdefense, to avoid losing to the ♦K.  Plus a heart lead through dummy would not have been welcomed.  My target should have been only seven tricks and I needed a third diamond trick to get me close.  What do you think?

When I looked at the hand record, I realized that not only would continuing a diamond have probably led to a seventh trick — I would have three diamonds, two clubs and the ♥A, while the opposing major suit singletons could make matters difficult for the opponents to cash three major suit tricks to add to their three club tricks and one diamond trick — but double dummy play could lead to eight tricks by endplaying East in a far-fetched way …

Dealer: East Vul: EW	North ♠ KT854 ♥ 9 ♦ QJT6 ♣ KQ4
West ♠ 6 ♥ KT5432 ♦ 953 ♣ T98		East ♠ AQJ9 ♥ J ♦ K82 ♣ A7653
	South ♠ 732 ♥ AQ876 ♦ A74 ♣ J2

Had I won the club lead in hand (North) and taken three rounds of diamonds to fell the king, East would be stripped of diamonds.  The ♥A(!) would strip East of her heart.  Next I could have played ♣J.  Whether East wins the ♣A now or later, she can be thrown in with a black suit and cash two spades and three clubs.  However, she would have to return a spade to my hand, where lies the long diamond.  That would be one spade, one heart, four diamonds and two clubs for me for the +120 I had sought but achieved -50.

Play suggestions, single dummy?