The_Badger, on 2017-September-17, 01:34, said:
Partner can't have the ♥AK as he would led ♥s, so what has he got? 8 card ♥ suit due to vulnerability. ♦ lead is probably a singleton or doubleton at most. Why hasn't he led one of the other suits? Mmmm....
Both you and dummy are both 5-4-2-2 so what does that leave partner and declarer with? If partner has led a singleton or doubleton, he will be 8-2-(3 or 2-1). What's that leave declarer with? 8 or 7 card ♠ suit headed by an honour. 3 or 4 ♦s.
The lead is important as partner can't have a higher ♦, so looks like declarer has at least good ♦ intermediates. I think I've seen this defensive scenario before in one of Kelsey's books.
No entry to dummy, except on the opening lead, but declarer can't get back to hand to draw trumps and is locked in his hand thereafter, and that means he has to lose two ♦s if partner has led a singleton.
So covering the lead won't help you one jot, whether it's a singleton or doubleton. So you have to duck with the East hand whatever ♦ declarer plays.
That's taken me a good 15 minutes to work out. Phew!
Nicely done. Maybe this was too hard to work out in the time constraints of BBO. For the record, the S-W hands: