When you open a suit and find that it is dummy’s strength do not
attempt to win the second trick if the dealer leads through your
hand, that is, unless you can mark the dealer with no other card of
the suit to lead; by taking the third round instead, you will often
save a trick or two.
A♠ 9♠ 7♠ 6♠ 5♠ 4♠
x-------x
| Y |
K♠ 10♠ 8♠ 2♠ | A B | NONE
| Z |
x-------x
Q♠ J♠ 3♠
In this case the dealer takes the first trick with the jack and leads
the queen. No attempt should be made to cover the card. In this way
the dealer is forced to win the third round and dummy’s suit is
blocked.