With the hand below, South opened a game force, then bid spades next round. South has one obvious diamond loser and the chance of losing something in hearts, but after North showed spade support, South decided that slam was worth a go. Perhaps North would have a useful card (such as the HQ) or the hearts might come good (on a successful finesse, for example).
Plan as South your play in 6S, on the lead of the CA:
NORTH
♠ T62
♥ 53
♦ 65
♣ Q98632
SOUTH
♠ AKQJ93
♥ AKJ98
♦ A7
♣ —
North has no helpful honour for South, but the heart shortage offers the chance to ruff the losers in that suit. As usual, this “ruffing in the short hand” is the task that needs to be fulfilled before trumps are drawn. Accordingly, declarer cashes the A-K of hearts (with the opponents following, low) then plays another heart, with West contributing the 10. What should dummy play?
If hearts are 3-3, it doesn’t matter which trump you ruff with, but if they are 4-2, a low trump would probably be overruffed. Therefore declarer called for the S10, while East flamboyantly discarded the DK, an emphatic signal for that suit. How should declarer proceed from here?
Drawing trumps would leave South with a loser in each red suit, so that is not an option. Almost all players, however, have a blind spot as to the actual winning line. Ruff a club to get back to hand; but what next?
Another heart is led from hand, and West perforce contributes the queen. Dummy could ruff, but as we already discussed, East will surely then overruff. There is a neat little alternative to this, however.
The cute play that is needed is to throw a loser on a loser. Discard a diamond from dummy. There are several variants of the loser on loser play but in this case, the benefit is in swapping the suit that dummy can ruff – from hearts (where an overruff is likely) to diamonds where it is extremely unlikely that East can overruff.
This loser play succeeds, because the full hand is as shown:
Contract: 6S by South
NORTH
♠ T62
♥ 53
♦ 65
♣ Q98632
WEST EAST
♠ 5 ♠ 874
♥ QT42 ♥ 76
♦ 9432 ♦ KQJT8
♣ AKJ7 ♣ T54
SOUTH
♠ AKQJ93
♥ AKJ98
♦ A7
♣ —