Entry squeeze

An entry squeeze exerts pressure by threatening the "length" of a defender's holding in a side suit. In many familiar squeezed positions, such as a simple or double squeeze, the rank of a defender's holding prevents declarer from cashing a threat until the squeeze has matured. This situation is also present in entry squeezes, but in addition a defensive holding interferes with declarer's entries, preventing declarer from effectively going back and forth between his hand and dummy.

The entry squeeze is sometimes described as a "non-material" squeeze. The entry squeeze may weaken a defender's holding in a suit where declarer can already take winners, but cannot take them in the preferred hand or in the preferred order. Therefore, it is only in part a squeeze against high cards, and so is not entirely material.

Geza Ottlik and Hugh Kelsey [Adventures in Card Play, Gollancz, 1979] give this example:

BridgeHand
K 7|8 4 3|K 6 5 2|J 8 4 3
10 8 5 3|10 7 5 2|J|9 6 5 2
A Q 6|A J 9|9 8 7 3|Q 10 7
J 9 4 2|K Q 6|A Q 10 4|A K

Choosing the fourth best in his longest and strongest suit, West leads the Spades3 against 3NT. East plays three rounds of spades, declarer winning the third with the SpadesJ and discarding dummy's Clubs3. South cashes the DiamsAQ, on which West discards a heart.
The position is now:

BridgeHand
-|8 4 3|K 6|J 8 4
10|10 7 5|-|9 6 5 2
-|A J 9|9 8|Q 10 7
9|K Q 6|10 4|A K

Declarer would like to lead toward his HeartsKQ twice, but his entry situation is such that he can get to dummy in diamonds once only. If he thinks of it, declarer can now play the Spades9, a losing squeeze card, to West's Spades10. So doing destroys East's hand.

If East discards a club, declarer can subsequently unblock the ClubsAK and score the ClubsJ.If East discards a heart, declarer can establish two heart tricks with only one lead from dummy.If East discards a diamond, declarer gets "two" entries to dummy: he overtakes the Diams10 with the DiamsK, leads a heart toward his HeartsK Q 6, and later, if necessary, leads the Diams4 to the Diams6, for another heart lead toward his remaining honor.
Ottlik and Kelsey summarize this entry squeeze as follows [Ibid.] : "Those silly little diamonds in the East hand have a function after all. Idle, irrelevant or immaterial as they may be called, by their mere existence they also serve. They stand and wait, in the way, blocking traffic, hindering enemy lines of communication. And having this value, however silent and hidden, they are subject to the pressure of a squeeze."

Another Ottlik – Kelsey entry squeeze:

BridgeHand
J 7 4|A K Q J|A Q|A Q J 6
10 9 8 6 2|10|K J 6|K 9 7 3
K 3|9 7 6 4 2|9 8 4 2|8 5
A Q 5|8 5 3|10 7 5 3|10 4 2

North overbids wildly to 7NT and West leads the Spades10. South unblocks dummy's Spades7, East covers with the SpadesK and South wins. In a sense, declarer has 13 tricks: three spades, four hearts, two diamonds with the finesse, and four clubs with repeated finesses. But there aren't enough apparent entries to the South hand to take all those finesses.
South finesses the DiamsQ, cashes the DiamsA, and runs the hearts. The fourth heart squeezes West (South throws the Diams7):

BridgeHand
J 4|J|-|A Q J 6
9 8|-|K|K 9 7 3
3|9 7|9 8|8 5
Q 5|-|10 7|10 4 2

A club discard lets South pick up the clubs with two finesses, using the Clubs10 to force a cover or retain the lead, so only one entry to the South hand is needed. A spade discard gives South an additional entry, so that he can overtake the SpadesJ with the SpadesQ, finesse in clubs, and finally lead to the Spades5 to squeeze West between clubs and diamonds.
But suppose that West discards the DiamsK on the fourth heart. Now, Spades4 to the SpadesQ and the Diams10 is cashed. West throws the Spades9 and dummy the SpadesJ. The Spades5 is cashed, West is finally forced to discard a club – and "dummy" is one-suit squeezed (!) in this position, with dummy to play:

BridgeHand
-|-|-|A Q J 6
-|-|-|K 9 7
-|9|9|8 5
-|-|-|10 4 2
So, declarer does not lead dummy's Spades4 after West discards the DiamsK. Instead, he leads dummy's SpadesJ and overtakes with the SpadesQ. Now when South cashes the Diams10, West must either discard a club a trick earlier, while dummy still has an idle spade, or allow South a re-entry with the Spades5. This would not have been possible if South had not unblocked the Spades7 at trick 1.

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