A sacrifice is a deliberate bid of a contract in duplicate bridge that is unlikely to make in the hope that the penalty points will be less than the points likely to be gained by the opponents in making their contract. In rubber bridge, a sacrifice can be also made in an attempt to prevent the opponents scoring a game or rubber on the expectation that subsequent deals can be won to offset the loss of points. Owing to the difference in the methods of scoring, a sacrifice in rubber bridge is much less likely to be advantageous.
In duplicate bridge scoring, making a game contract yields 600 or 620 points vulnerable and 400 or 420 points non-vulnerable, depending upon the strain and assuming no overtricks. Accordingly, a sacrifice will turn out profitable if the resultant loss in points is less than these amounts.
|Opponents' game points||Undertrick penalty points
in a doubled contract
|Vulnerable||600 or 620||200||500||800||100||300||500||800|
|Not vulnerable||400 or 420||200||500||800||100||300||500||800|
Determination of the most number of tricks than can be lost to satisfy this condition is dependent upon the vulnerability of each partnership, i.e. whether one, the other, both or neither are vulnerable. The determination is also based upon the assumption that the opposition will likely double the sacrifice bid thereby increasing the penalty points. The table at left summarises the various scenarios and outcomes.
In summary, when the opponents are likely to make a game contract, a sacrifice bid is viable (i.e. one will still receive a positive relative duplicate score) if one can go down no more than 3 tricks if vulnerability is favourable, 2 if equal and 1 if unfavourable.
Similar reasoning can be drawn for potential slam and partscore contracts.
A sacrifice most often occurs when both sides have found a fit during bidding (8 cards or more in a suit), but the bidding indicates that the opponents can make a game or slam contract. Also, it is possible to perform an advance sacrifice, when it is more or less clear that the opponents have a fit somewhere and greater strength. For example, after the partner opens 1♦ and RHO doubles, the following hand is suitable for a bid of 5♦, outbidding opponents' major suit game in advance:
As seen in the table above, vulnerability significantly affects the sacrifice: success is most likely if the opponents are vulnerable but the sacrificing side is not. At equal vulnerabilities, sacrifices are less frequent, and vulnerable sacrifices against non-vulnerable opponents are very rare and often not bid deliberately. Also, the specific duplicate scoring method affects the tactics of sacrifice - at matchpoint scoring, −500 or −800 (down 3 or 4) against −620 is a 50/50 bet on a top or a bottom score, but at international match points (IMPs) it can gain 3 IMPs (120 difference) but lose 5 (180 difference), making it less attractive.
However, if it turns out that the sacrificing side misjudged, and that the opponents' contract was unmakeable (or unlikely to make), the sacrifice is referred to as a false or phantom one. A false sacrifice can cost heavily, as the sacrificing side has in effect turned a small plus into a (potentially large) minus score.
The Law of total tricks can be a guideline as to whether the sacrifice can be profitable or not.
Sacrifices are practically always made in a suit contract; sacrifices in notrump are extremely rare, but can occur, as in the following deal:
|♥||K 8 7 4|
|♦||J 9 7 4|
|♣||Q J 5|
|♠||Q 10 8 5 3||
|♠||K J 9 7 2|
|♥||A Q J 6 3||♥||10|
|♣||K 8 4||♣||10 9 6 3 2|
|♥||9 5 2|
|♦||A K Q 10 8 6 3|
The bidding starts:
1. Michaels cuebid, indicating both majors.
South can see that East-West have a huge spade fit and that it's quite possible that they can make 4♠. However, the best bet seems to be 4NT rather than 5♦, since it requires a trick less, while there's not much indication that 5♦ would provide more tricks than 4NT. Indeed, 4NT is down one and 5♦ down two.