You arrive in 4♥ as South. West leads the ♠A K Q (East follows) and switches to the ♦J. What’s your plan for 10 tricks?
You start with nine top tricks: (five hearts, one diamond and three clubs). You could decide to
simply draw trumps and play the top clubs. If the suit splits 3–3, you’re home. But what if clubs divide 4–2? Can you handle that? Yes, if trumps are no worse than 3–2.
Here’s the plan: Win the ♣A and cash the ♦K Q, leaving one trump outstanding. Next cash the ♠A and play a club to the king. If this gets ruffed, you couldn’t make the contract anyway. Now ruff a low club in your hand, cross to the preserved trump ace (drawing the last trump) and cash the ♠Q and the last club, pitching diamonds from your hand. What if trumps were 4–1 or 5–0? Then you need clubs to split 3–3.