These hands are from the San Diego Unit Game on September 2, 2018.
West: ♠QJ5 ♥K73 ♦863 ♣KJ73
East ♠AK4 ♥A10982 ♦9 ♣Q986
You and your partner compete to 3♥, after N/S push to 3♦. A low diamond is led. North takes the ♦A and returns a low (fourth-best) diamond which you ruff. You play a heart to the ♥K and the ♥J falls on your right. Upon a low heart from Dummy, RHO shows out, playing a low spade. You take your ♥A. Since you must budget for two heart losers, it is time to develop the clubs. You play a low club to the ♣K in Dummy because you want to play toward the hand with two honors on the first round of the suit. RHO takes the ♣A and returns a spade. You take the ♠A in hand to keep the spade entries on both sides of the table. The only risk to your contract is if clubs are 4-1. RHO (North) is known to have started with four diamonds and one heart. It appears RHO also started with spade length, so if anyone is going to have long clubs, it will be North. You must play a low club from your hand toward Dummy. If South ruffs, you don't care. If South discards, you win the ♣J and play a low club back, finessing North for the ♣10. If you carelessly take the spade on Dummy with ♠Q and play the second round of clubs to your ♠Q, you are losing two club tricks and your contract.
South (Dummy): ♠1032 ♥873 ♦6432 ♣K742
West: ♠KQ5 ♥KJ106 ♦KJ8 ♣A53
Because Kent Hartman and I play Weak NT (except in fourth seat), I opened the West hand 1♣ and North overcalled 1NT. Partner passed and led the ♠6. I played the ♠Q and Declarer took the ♠A and played a club to the ♣K. I took the ♣A immediately (Declarer has long clubs since partner did not lead my suit) and played the ♠K. Partner played the ♠4. I continued with the ♠5 and partner played the ♠J. Then partner ran off the ♠8 and then the ♠9, finishing the suit. I had to find two discards so I discarded the ♣5 and then the ♣3, the order a suit preference for hearts (the higher ranked suit) because my hearts were slightly better than my diamonds. Plus, Declarer discarded the ♥4, the ♥9 (encouraging me that partner might have the ♥Q) and then the ♦9.
Alas, I was paying too much attention to my discards and Declarer's discards, and did not think enough about my partner's play of the spade suit. My partner played the ♠4 on my ♠K—which does show that he started with five spades. However, its most vital message is to suggest a possible entry in a LOWER side suit (in case I had started with ♠KQ doubleton). After winning his ♠J, partner played his ♠8 and ♠9 from the BOTTOM UP—again indicating the lower of the side suits. Had I been paying attention rather than being sucked in by Declarer's heart discards, I would have discarded a LOW heart (standard attitude) or played my club discards from BOTTOM UP rather than top down. Then, partner can lead a diamond to my ♦K. I return the ♦J and partner gets four diamond tricks. On that scenario, Declarer is down 3, instead of +90.