This deal was played in the 2017 Tarrytown Regional, South held:

K43
AJ5
K43
A1043.
He opened 1NT and partner transfered to 2. Responder next bid 3. Since the partnership is now forced to game, opener's 3 is stronger than 4. With such good controls opener should bid 3. Responder now made a 4 control bid, opener bid 4 and after RKC, the pair landed in 6. The 10 was led:

Q109765 6 AQJ109 K

K43 AJ5 K43 A1043

Counting the losers (from the perspective of the long-trump hand, North), the only issue is the trump suit. The best play is to lead low from dummy towards the king. Why? If they are 2-2, not much matters, and if there is a singleton ace, it is just as likely to be in either hand. But, a 4-0 break (which happens about 10% of the time) can be picked up sensibly only one way. If West has 4 spades, starting with low to the king will reveal the position (starting low to the queen can't pick up 4-0 the other way). Since all the 2-2 and 3-1 breaks are just guesses, declarer might as well play in the way that picks up the relevant 4-0 break.

Declarer captured East's Q with the ace, and not wanting to subject himself to a diamond ruff, crossed to the K at trick two. He led a low trump from dummy and was rewarded when RHO showed out. Declarer put up the king and West took the ace. A heart was returned, and declarer realized he couldn't make the contract. He ruffed in dummy and could get back to his hand only once. But, he needed two entries for two spade finesses. This was the Real Deal:

Vul:Both Dlr: South	Q109765 6 AQJ109 K
AJ82 109872 7 J87		-- KQ43 8652 Q9652
	K43 AJ5 K43 A1043

After winning the A at trick one, declarer crossed to dummy with the wrong card. When he crossed to the K and played a spade to the king and ace, he had only one entry remaining in his hand (the K). He should have ruffed a heart in dummy at trick two. Then, when the K loses to the ace, declarer still has two entries (the K and the A--by overtaking). Dummy's K was a red herring. It tempted declarer into using it prematurely. If dummy's club were a low singleton, likely declarer would not have been so careless with his entries.