When defending it is essential to stop and think about the entire hand
rather than automatically returning your partner's suit.
Take a look
at this example.
Scoring: Matchpoints
Hand #5
Dlr
E
Vul
N-S
J2
1086
A85
109643
K1087
KJ54
72
Q52
AQ53
972
QJ93
87
964
AQ3
K1064
AKJ
West
North
East
South
Pass
1NT
All Pass
BIDDING: South held a standard 1NT opener and that closed
the auction.
PLAY: West led his fourth best spade and East won the
queen. The play of the queen was to discover if he held a second
entry to his hand. Realizing four or five
spade tricks would not defeat the contract, East shifted to the heart
seven. The seven was an attitude card that said, "don't return
this suit". If he had instead led the deuce, he would be showing
a higher honor and would welcome a return. South played low
on the heart and West won the jack. West continued with a second
spade to East's ace. Now a second heart from East was won by
declarer with the ace. South then played the ace, king, and jack
of clubs with West winning the third round. West now cashed his
last two spades and two hearts to beat the contract two tricks.
Note if East had routinely returned a spade at trick two, declarer
would succeed with seven tricks.