S/All		♠	K 10 9 5 4
		♥	10 3
		♦	9 7 5
		♣	K Q 4
				♠	A 8 7 6 3
				♥	8 6 5
				♦	Q
				♣	A J 9 2

¹ 'tell me more about your holding in the majors'
² four hearts, no three spades

West leads the ♦4, fourth best, East's ♦Q winning (South the ♦6). East switches to the ♥8, South wins with the ♥A, West the ♥4.
South continues with the ♣3, West plays the ♣7, dummy the ♣K, to East's ♣A.
East plays another heart, South winning with the ♥H, West the ♥2. South now plays the ♣5, West the ♣6, to dummy's ♣Q and then another club to East's ♣J, West discarding the ♦2.
How should East continue the defence?

Solution

East can reconstruct the entire deal just by counting. South showed four hearts in the bidding and turns out to have four clubs as well. Partner has led the ♦4 and has discarded the ♦2, showing a five card suit (if he had started with six diamonds, ♦xxx432, he would have discarded the ♦3 instead of the ♦2).
South began with 1-4-4-4 therefore, his jump to 2NT was rather unorthodox.
For his jump South certainly holds all four face cards in hearts and the ♦AK. This adds up to 17 points only, so his singleton spade is either the ♠J or the ♠Q. Probably the ♠J, since holding the ♠Q he would have played it immediately.

The deal is therefore (red cards have been played):

S/All		♠	K 10 9 5 4
		♥	10 3
		♦	9 7 5
		♣	K Q 4
♠	Q 2			♠	A 8 7 6 3
♥	9 7 4 2			♥	8 6 5
♦	J 10 8 4 2			♦	Q
♣	7 6			♣	A J 9 2
		♠	J
		♥	A K Q J
		♦	A K 6 3
		♣	10 8 5 3

Does East spot the danger? If he fails to cash the ♠A now but instead plays his fourth club (or a heart) directly, he creates major problems for his partner.

On the fourth club West can shed a heart but then declarer cashes his remaining two hearts. What can West do?
- If he throws a spade, South cashes the ♦AK. There are two tricks left. South plays his ♠J, West's bare ♠Q shows up, dummy plays the ♠K. East can win but has to give dummy the last (spade) trick.
- If West discards a diamond, South collects three diamond tricks.

It pays to stop and think in seemingly 'standard' situations, like the one East was in after winning with the ♣J. The author (Dutch Youth International Frank Visser) was East here and 'forgot' to cash the ♠A on the moment suprème, thereby manoeuvring his internetpartner into this squeeze.

The lesson is clear: never stop counting!

PS: Note West encouraged when East switched to a heart. He need not (and should not) have done so: East knows West's four card suit from the bidding. West should only encourage holding an honour card.

PPS: Declarer makes his contract if he plays (finesses!) spades himself directly. This way he ends up with four tricks in hearts, two in diamonds, two in clubs and one in spades.