[c2]

in pair match, there always some unique play or situation, here is one, it was played in a 55% robot rebate match, which is my favorite match style, recently.
I have made 2 mistakes in this deal, however, its an educational deal, so I would like to share it with those guys who play 55% matches.

it was the last one of 12 boards when this deal come, and my overall percent score for all of the previous boards is a little more than 50, by simple calculate, I must got 100 on this one to win the game(1.5 BB$).

rho opened 4d, this is my hand

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try to got a top, the best chance is to play a different contract from others and try to score more pints.
what will others do in this hand, obviously, x or 4s is common choices, so they are excluded from my plan.
I bid 4nt and buy the contract.

LHO lead the famous seven of diamond, and I can see the dummy's hand

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aha, the adventure in bidding got a very well effect, it seems no other contracts is as well as 4nt, so we just try to make it.
we have two diamonds two spades and very likely five clubs, where is the tenth trick coming from?
after a little meditation, I decide to setup one more spade trick.

win the open lead in dummy, I lead a spade, RHO play S10 and I ducked, it is often good practice to duck early, since opponents don't know much of what you are doing,

[c2]

the robot on the east continued with queen of spade (he/she must have thought for a while here ), I try to figure out the distribution of spades, I know sometime robot will put up the honor in a doubleton, so maybe it's from QJ10 this time, and we will have an overtrick!
the eager to get a top drive me to take the spade queen and catch another spade trick.
alas, east discard a diamond, I have to concede another spade to west to setup a spade trick, now bad things happen, west just cash two hearts and leave me one down!

[c2]

the whole deal is:

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[gszes]

Looking at the shortage of entries you need to try and come up with distributions that match the bidding. You are pretty much forced to assume clubs are 32 since you do not have the ability to deal with 41. That along with the 4d bid give you strong reason to assume rho has ten minor suit cards and thus only 3 major suit cards. Hoping for 33 spade means you are hoping rho is void in hearts and lho decided to not bid holding AKQTxx of hearts in first chair that is a bad assumption. It is far more likely rho will hold 2s and 1H or vice versa.

IMHO you will probably be much better off winning trick 1 in dummy and leading a low heart hoping rho has a singleton honor and when you win the dia return in hand lead another heart
and finesse lho for the heart T. This will work if rho cannot find a spade switch when they win their heart honor. It might also work if rho has the heart 9 and lho fails to find a spade switch.

Having said the above:

Defense is hard and there is definitely a case to be made for opting to run your clubs right away hoping lho misguesses and tosses a couple of spades from 4 of them (they do not know about your spade length). The huge downside is what do you pitch from hand on the 4th 5th club? You have to pitch ahead of lho. It is hugely unlikely pitching hearts will fool anyone but if you decide to pitch 2 spades this might convince lho of the need to hold heart length and when you lead your dia from dummy to your K at trick 7 hope against hope lho is fooled and reduces to 2s and 4h.

The first LOP looks for a specific lie of the cards and a little on "fog of war" while the 2nd LOP is hugely "fog of war" dependent. The main point is to look for plausible LOP considering the evidence obtained in the bidding and play of the hand:)

[c2]

hi gszes, thank you for the commendation. I agree with you. I have missed the right play, that is why I wrote this post.
besides the distribution you have said, there are other clues lead us to the right direction, since there is only one truth.

As west didn't start open lead with hearts, surely he did not have all three heart honors, so it almost double dummy, the best line is to setup a hear trick.

in the actual line of play, when east continue spade with Queen, I should have ducked again, it is quite possible robot can't find the heart switch.
As gszes have mentioned, 33 spades split is impossible.