Mark Twain said, "I was born modest; not all over, but in spots."
In yesterday's deal, South would have made his slam if he had held the trump seven-spot instead of the six. In today's deal, South is in six hearts. What happens after West leads the diamond king?
On the second round of the auction, North raised to two spades, worried about the low doubleton diamond. Then, over South's three-heart rebid, North did very well, control-bidding four clubs. This announced four-card heart support, the club ace and a hand she really liked. (With four hearts and an unexciting hand, she would have raised to four hearts. Without four hearts, she would have continued with three spades or three no-trump.) South then bid what he hoped he could make.
The diamond lead was lethal. South won with his ace, cashed the club king, crossed to dummy with a spade and discarded his last two diamonds on the club ace-queen. Then came the heart queen. When East won with his ace and led a club, declarer ruffed with the heart nine, but West overruffed to defeat the slam.
Then South realized that, like in yesterday's deal, if dummy had had the trump seven and West the six, the slam could have been made. In the end-position, when East leads the club jack, South can ruff with his king, then lead the heart nine to pin East's eight and draw trumps without further loss. Of course, that play would not have looked so clever if East had begun with ace-10 doubleton.