Loser-on-Loser

Here is a defensive Trump Promotion (spades are trumps):

If you as South are on lead, you can cash the ace of trumps felling West’s king, and enjoy the queen. But, infuriatingly, if East is on lead and selects a diamond (the suit in which West is void), you cannot avoid losing to West’s king: if you trump with the queen, West overtrumps, and if you trump with the ace, West discards. 

Sometimes there is nothing you can do to prevent such a Trump Promotion. Sometimes there is.

What happened
West led ♠ 10, and East won ♠ Q, cashed ♠ A, and followed with ♠ K. Declarer ruffed low, but West overruffed, and the defence had to come to a third-round club trick. Down one.
It was pretty clear that West held no more spades, having led “high-low” and East having opened the suit. However it would have done declarer no good to have ruffed the third spade high (with ♥ K/♥ A). West would discard, and would come to a promoted trump trick (plus a club). Down one. Is there a way out?

What should have happened
The solution (at Trick Three) is to throw away a club, which is a loser anyway. This “Loser-on-Loser” play stymies the defence. If East leads a fourth spade, declarer discards (or ruffs low), and dummy can overruff West if necessary. If East leads anything else, declarer can win, draw trumps, and claim. 10 tricks and game made. Neat.

If you remember one thing...
Look out for Loser-on-Loser plays - perhaps to prevent a defensive Trump Promotion.