This is the second of three exercises following the article 'Ruffing: sometimes it's good... but sometimes it isn't ***, which has been published earlier.
To read that article, click Ruffing at bridge play.
For exercise 1, click: Ruffing at bridge play- Exercise 1.

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

¹ Splinter: singleton or void in clubs; diamond fit; slam invitational
² Control showing (a dangerous bid, since most pairs would consider this 4♥ bid to show a playable spot; meaning South tells North he may pass if his — North's — slam try was a minimal one; North would then be expecting something like ♥Kxx in South. This NS-pair, however, has agreed that 4♣ rules out hearts as trumps)
³ I've done enough
⁴ North has shown willingness to play 6♦ but has denied a spade control; since South has the ♠A and a very good hand (in view of his 2♦ bid) he surely must bid the slam

Perhaps North was a bit too eager, for this slam is too ambitious.
West leads the ♣3. How should South play?

Solution

Declarer is looking at two spade losers. At first sight he can pitch neither one of South's nor one of dummy's spades on a high card in the other hand.
The chance that declarer, by playing spades himself, can avoid losing two spades, is not a good one. He has two chances, which he cannot combine:
- East has both the ♠K and the ♠Q. In that case the winning line of play is to play a small spade to South's ♠J. Chance of success: 24%.
- East or West has ♠Kx or ♠Qx or the bare ♠KQ, or West has a bare spade honour. In that case the winning line of play is to draw EW's single trump, cash the ♠A, eliminate the hearts and clubs (by cross-ruffing) ending in dummy and play the ♠7 from there (observe carefully what will happen next if the lay-out is as South hoped for). Chance of success: 16%.

On closer inspection there is a rather good chance after all that declarer can pitch one of dummy's spades losers on a winner in South. Which winner? A high club!
Probably it's declarer's best chance: he has to hope West has underled the ♣K (or even the ♣A!):

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