The opening lead is the first card played in the playing phase of a contract bridge

Contract bridge

Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

 deal. The defender sitting to the left (LHO) of the declarer is the one who makes the opening lead. Since it is the only card played while dummy's cards are still concealed, it can be critical for the outcome of the deal. Making the best opening lead is a combination of selecting the best suit and then the best card within that suit.

Selecting the suit

Considerations are:

• Good suits to lead may be:
  • a suit partner has bid
  • a suit not bid by declarer's side
  • a suit bid by LHO
• Against a suit contract:
  • a short suit lead may be good, but only when it is likely that partner will be able to obtain the lead and return the suit.
  • but leading a suit containing an ace may be bad
• Against NT contracts
  • leading a long suit may be good
  • leading a suit in which partner could have length may be good
• Choosing an aggressive or safe lead is important:
  • defeating some contracts calls for aggressive leads, while others call for safe leads. For example, take a look at the following deal:

North and South have reached a contract of 4, which has some possibilities. At first glance the declarer seems to be losing a spade, a heart, maybe a diamond if the finesse

Finesse

In contract bridge and similar games, a finesse is a technique which allows one to promote tricks based on a favorable position of one or more cards in the hands of the opponents....

 fails and a club or maybe more. However, if the opening lead is the 2 (a safe lead) Declarer will find it much easier to make the contract because he will have time to set up the diamond suit. The 4 lead (an aggressive lead) will make his job more difficult.

• • the best of both worlds is a lead that is both aggressive and safe, for example leading a suit headed by an honour sequence will give little away and may well set up tricks for the defence

Selecting the card

Partnerships may choose their own method of "carding". The following is considered fairly standard (mainly Klinger 1994 ):

• Leading a singleton against a suit contract is recommended only when defender has a trump stop
• Other short suit (two or three cards) leads:
  • from a doubleton lead the higher card, thus from 93 lead the 9
  • from a three card suit
    • if headed by an honour (not a sequence) lead the lowest, thus from Q92 lead the 2
    • if all cards are low, there are three schools of thought:
      • TON "top of nothing" – lead the top card. It has the advantage of denying an honour, but is ambiguous with a lead from doubleton,
      • MUD "middle-up-down" – lead the middle card, and play the highest card next.
      • the lowest card (least popular)
    • if headed by a sequence (even two cards) lead the highest. From QJ2 lead the Q
• long suit (four cards or more) leads:
  • from a sequence of honours lead the highest, thus from KQJx lead the K
  • from a suit containing an internal sequence lead the top of that sequence, thus from KJ109 lead the J
  • from a suit headed by an honour, defender generally leads the fourth best card, allowing partner to employ the rule of 11
    Rule of 11
    In bridge, the rule of 11 is applied when the opening lead is the fourth best from the defender's suit. By subtracting the rank of the card led from 11, a defender can figure out how many cards are higher than the card partner has led...
    
    
  • from a honourless suit, the highest or second-highest is normally led, especially against suit contracts; some partnerships lead fourth best against notrump though.
• From hands containing both A and K
  • from AKx or AKxx etc lead the A
  • from AK doubleton lead the K
• Against a suit contract, many partnerships reserve a special meaning for the lead of a 10 .. it promises a touching card J or 9 and a non-touching higher honour e.g. K J10, K 109, Q 109.

Difficulties

Ambiguities can arise from this standard method, thus:

• A defender would lead the 2 from K532 and from K32 ... does he have a four-card suit or not?
• Similarly a defender may lead the 2 from 9432 and from KJ92 ... does he have an honour or not?
• A defender would lead A from AK2 or from A32 ... does he have the K or not?
• A defender would lead the K from AK doubleton and from KQx ... does he have the A or the Q?

To overcome these problems various conventions have been devised:

• Rusinow leads
  Rusinow leads
  Rusinow leads is a bridge convention used as part of defensive carding. Rusinow leads are commonly used only on the opening lead against a suit contract....
  
   - overcomes the ambiguity of a K lead:

When West leads the K East may be confused as to the nature of his holding. If he is leading from KQ East will want to encourage, but if leading from AK East will want to discourage. Rusinow leads recommend leading the second of touching honours and the above confusion is largely eliminated. Rusinow leads are now considered a standard part of the Roman Club

Roman Club

Roman Club is an artificial bridge bidding system devised in the 1950s by Giorgio Belladonna and Walter Avarelli of Italy's Blue Team. They used it to win twelve WBF World Teams Championships, three Olympiads and numerous European and National titles...

 system.

• Journalist leads
  Journalist leads
  Journalist leads are an Opening lead convention in the game of contract bridge. The method is designed to fix some problems with the standard opening lead system...
  
  - overcomes the ambiguity of a J lead.

The leader might have J1094 or KJ104. The convention proposes that the opening lead be the Jack from the first sequence and the 10 from the second in order to better inform his partner about the nature of his holding.