[nige1]

3N would have been simpler but South is declarer in 5♣ on the lead of ♠A ♠2 ♠Q ♣4. Both defenders follow to ♦KA.
I'm ashamed to admit that this deal is based on another contract that I butchered, recently. It illustrates a useful simple common basic technique, so I'm rubbing my nose in it by posting it here.

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[Douglas43]

Thanks for posting Nigel. It's a classic hand. Looks like you should play a diamond and, instead of ruffing, ditch a heart from dummy? Then you can ruff a heart in dummy.

This loser on loser play doesn't cost anything when diamonds are 3-3, because you would not otherwise be able to avoid a heart loser. But it's not an easy play to spot at the table...

[Cyberyeti]

Douglas43, on 2020-December-03, 09:23, said:

Thanks for posting Nigel. It's a classic hand. Looks like you should play a diamond and, instead of ruffing, ditch a heart from dummy? Then you can ruff a heart in dummy.

This loser on loser play doesn't cost anything when diamonds are 3-3, because you would not otherwise be able to avoid a heart loser. But it's not an easy play to spot at the table...

It's not 100% foolproof but looks the best shot.

It depends if you think W will overcall with AK, 1098765, ????, x or double with AKx, KQ, ????, xxxx with W holding a 3721 with ♠QJx, ♥J 7th and maybe a diamond quack and not overcalling.

[nige1]

3N would have been simpler but South is declarer in 5♣ on the lead of ♠A ♠2 ♠Q ♣4. Both defenders follow to ♦KA.
I'm ashamed to admit that this deal is based on another contract that I butchered, recently. It illustrates a useful simple common basic technique, so I'm rubbing my nose in it by posting it here.
+++++++++++++++++++++++++++++++++++++++++++
I ruffed the 3rd diamond and could not recover
Douglas43 and CyberYeti found the successful loser-on-loser play that I missed:
- Discard a ♥ on the 3rd ♦ and
- Discard another heart if West continues with a 4th diamond
- Now you can ruff a ♥ in dummy.

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[Cyberyeti]

It would be unfortunate if you got one of the layouts where it failed (either because E pitches 2 hearts on the diamonds then overruffs you, or pitches 2 spades and uppercuts with a stiff trump), but it seems to work a very large percentage of the time.