EARLY in the play the defenders are at a disadvantage: they cannot see their combined assets, so if you give them a guess they will often guess wrong.
On this deal from the Senior Teams at the 2011 EBL Open Championships in Poznan South found himself in a normal enough game. The only possible losers were three trump tricks and the queen of clubs. West led a heart to the single ace in dummy, and one declarer crossed to the king of diamonds to run the ten of spades, losing to the jack. When the club finesse lost he was one down and feeling unlucky.
The other declarer noted that there were very few missing high cards. He thought West was quite likely to have both ace and king of spades for his overcall. He feared that crossing to hand with a diamond might set up a ruff for the defenders, so he simply led a low spade from dummy at trick two. Easy for us to see that West should rise with the jack, but would anyone really do that? When the ten was won with the king declarer knew what to do in trump. He won the second round of hearts with the king and led a spade towards dummy, intending to go up with the queen if West ducked. West actually took the ace and played a third heart, giving a ruff and discard. This allowed declarer to dispose of his club loser and make an overtrick.