Then a shift back to diamonds gave the defense five tricks.
This gave him 12 tricks, and almost all the match points.
The club king will provide a discard, and that gives him nine tricks.
Since there are three cards played every trick, this gives us 17 tricks per hand.
Another heart led by East gave his partner two tricks in the suit.
He could not spare a club, which would have given South four tricks in that suit.
East realized too late that he would have done better to take his diamond king at some point, giving the defense six tricks.
A pointed-suit lead would have given the defense three quick tricks.
It was vital to avoid a diamond play from that side of the table, which would give the defense four tricks.
Driving out the ace will give him nine tricks, but he must think further.