Source: Getting Your Ducks in a Row By Paul Thurston
While I’m a firm believer in the defensive mantra that aces are made to capture kings and queens, knowing when to use one of those prime cards to win a trick while capturing a monarch can be just as important.
North-South’s practical approach to the auction landed them in a decent notrump slam that started with nine easy tricks in the majors after South won the 
K and crossed to the ace to confirm no horrendous split. That made declarer’s task relatively straightforward as he could easily arrange for one trick in each minor, so his twelfth would have to be a second diamond (possible if East had started with the ace) or a second club if West had been dealt the king.
Having arranged to be in dummy at Trick 3, South called for a low diamond and was pleased to win with the king. If that diamond had lost to the ace, South would have been reduced to having to find the 
K on his left, but the play seemed to indicate East had started with the missing ace. Accordingly, South cashed the rest of his hearts, perhaps to torture the defenders into having to find discards, before leading a low spade to dummy for another diamond play through East.
West’s producing the 
A to decapitate the queen was a good deal less pleasing to South than the first round of diamonds had been. However, he was only down one when West exited with a diamond and East couldn’t find another card in the suit after taking the setting trick with his jack.
Many defenders holding the West cards during the recent World Championships in Paris had an opportunity to make a classic deceptive play that might have been taken right out of a textbook on the subject. The problem with making this type of play is that it must be done without a telltale break in tempo and that is usually only possible if you recognize the situation from experience and/or study. Many pairs used the slightly non-standard application of Jacoby transfers as shown to reach the heart game declared by South. West cashed two high clubs and continued the suit to South’s jack. At that point, South’s problem was simplicity itself: with the trump ace still out, how could he avoid losing a second trump trick?
Two possibilities would allow this: if either defender were to hold a doubleton ace of trumps and declarer guessed which one, he could lead the first round of hearts through that defender and duck completely on the second round, the so-called ‘obligatory finesse’. Alternatively, either defender might hold the doubleton J10. The declarers who broached trumps by leading low towards the king never had a problem as the suit was favorably arranged for this play. However, many in the field led a low spade to dummy’s king to start trumps by leading low towards the Q in the closed hand. It’s irrelevant whether East plays the jack or ten but when South covers with the queen, West must seize the opportunity to play low like he’s never held a trump ace in his life! If West makes this fine ducking play without a ‘deep brown study’, declarer’s next play will assuredly he a low trump from both hands in an unsuccessful attempt to have the heart ace «fan air».
Lest you think ‘Third Hand High’ is an absolute prescription for defensive success, especially versus a slam where taking a trick gets you half-way to what you need, take a look at this layout from this year’s Canadian Open Teams. When North unleashed his partnership’s version of a limit raise, there was no holding South back. Today’s pair was using the popular Bergen Raise structure so that North’s response artificially promised a limit raise, the sixth trump presumably substituting for an extra high card or two. This motivated South to issue a general slam invitation that focused mainly on trumps, and by all sensible measurement North’s trumps were better than average for a limit raise. But the slam’s fate would be solely dependent on East’s play to the very first trick after West routinely led the top-of-a-sequence 
J and declarer played low from dummy. If East were a thoughtless subscriber to ‘Third Hand High’ or simply hated the thought of not taking his ace right away and losing it, he would grab his ace and South would have two spade winners, the second of which could be used to discard a club loser from dummy. And if East showed a bit more patience and played low at Trick 1? Well, then North and South could have a post-session discussion about what a limit raise should really look like!
As reported by Alasdair Forbes in a recent International Bridge Press Association Bulletin, a club player in Glasgow found a truly ingenious play that you might want to file for future utilization. South’s exuberant jump rebid is usually a bit of a barrage effort when an opponent has made a takeout double, but even so it would have shown super-human restraint for North to do less than jump to game. Sadly, game looks easily beatable with the defense holding three cashable aces but appearances can certainly be deceiving — just ask East after declarer played low from dummy on West’s spade lead. South had certainly given up nothing of a material nature with that highly unusual ducking play. Even if East had the ten to play to win the trick, de-clarer could always take a ruffing finesse and establish the two spade tricks he had coming, although not likely before the defenders had harvested their quota of three tricks. As it happened, East was convinced for all the world that South would have the 10 (wouldn’t you be too?) for that low play from dummy so what was there to make of West’s opening lead? With South contributing the seven on the first trick and almost certainly holding the ten, East decided that the missing spot cards told him one of the two hidden hands had started with a singleton spade (right!) and that it was West (wrong, oh so very wrong!). The suit preference return of the 9 for %Vest to ruff didn’t turn out exactly as East had envisioned when South discarded a heart, West followed suit and South soon thereafter chalked up his game bonus.