24. Slam Bidding

Bidding a slam (six or seven level) is one of the most thrilling (and scary) things in bridge. I’d say the most common error, especially at a club, is trying to get to a skinny slam. Most people aren’t going to do that, so if you do, you’re going to get a top or a bottom. And matchpoints is all about hitting it straight down the fairway on the bidding, and winning with cardplay and defense.


Blackwood is one of the oldest conventions, and has now been supplanted for suit slams by the Roman Keycard version. The same cautions discussed below for RKC also apply to plain Blackwood.


Blackwood and RKC are tools for avoiding bad slams, not for finding slams.

Be sure that any answer is acceptable, that you can still stop safely if you cannot bid slam. You can and must bid a six-level slam if you use Blackwood and then find you are off one Ace.

A bid of 4N, when it is not quantitative, asks how many Aces partner has. The responses are:

  • 5♣ for 0 or 4 Aces,

  • 5♦ for 1 Ace,

  • 5♥ for 2 Aces,

  • 5♠ for 3 Aces.

Following this, if our side has all four Aces, a bid of 5N asks how many Kings partner has, using the same scheme.

For example:

1♠ - 2♥
3♥ - 4N (Blackwood)
5♥(2 Aces) - 5N(Kings?)
5♦(1 King)

Be sure you’ve agreed to a suit before concluding partner’s 4N is Blackwood rather than quantitative.

Roman Keycard Blackwood (RKC)


Before bidding RKC be sure you are able to tolerate any of its replies. Be sure you’re going to bid the slam if only off one keycard. Off one keycard and the Queen of trump, do not bid the slam.

In a suit auction, 4N is almost always Roman Keycard Blackwood. If you are a beginner you can play basic Blackwood but you should learn RKC early on.

The responses are based on their being five keycards, which are the four Aces and the King of trump. If a trump suit has not been agreed to, 4N implicitly agrees (at least for the purposes of responding) to the last bid suit. So, for example, 1♥ – 1♠ – 4N is RKC for spades. The bidder in some circumstances may be intending to end up in some other (higher) suit or notrump but for now responder answers as if the last bid suit is trump, which it very likely is.

Responses to RKC

  1. 5♣ One keycard or four keycards

  2. 5♦ Zero keycards or three keycards

  3. 5♥ Two or five keycards without the trump Queen

  4. 5♠ Two or five keycards with the trump Queen.

    Also bid 5♠ with two or five keycards and enough trump to guarantee a 10 card fit, even if you do not have the Queen.

Responding with a (Useful) Void

  • 5N Shows zero or two keycards and a useful void.

  • 6 of any suit below the trump suit shows 1 or 3 keycards with a useful void in the bid suit.

  • 6 of the trump suit shows 1 or 3 controls and a useful void in a higher suit.

A void is not useful in a suit your partner bid.

The bids shown are the “1430” response. Switch the meanings of 5♣ and 5♦ and it is the “3014” responses. I use 3014 because 1430 won’t work for clubs: 4N - 5♦ means zero and is already past 5♣.

RKC is a tool for avoiding bad slams, not exploring for one. The person who bids it must be prepared for any of the answers.

When 4N is NOT Ace-Asking

A bid of 4N is not always RKC or Blackwood. Here are the exceptions:

  • A direct jump to 4N over 1N or 2N, or after a 2N rebid following a 2♣ opener, is quantitative..

  • After a 1N opener and transfer to a major, 4N is quantitative.

  • After 1N - 2♣ - 2M, 4N is quantitative. Responder can instead first bid 3W! (the other major) to agree on opener’s suit and show extras. Opener will bid a control and then 4N is Ace-asking.

  • After a 1x opener, a direct 4N is plain Blackwood. Responder has a self-sufficient trump suit and just needs to ask for aces.

Many pairs play various conventions in which RKC is invoked with some other bid. See Redwood for example.

When Not To Bid RKC

It is generally useless to bid RKC if you are missing two keycards and have a worthless doubleton (worse than Kx or Ax). The problem is that you learn nothing if partner replies, “One keycard”. You may or may not have two fast losers. In general it is necessary to think ahead and make sure you can take yes for an answer. Learning partner has two keycards but you don’t want to be in a club slam is an unpleasant experience.

When hearts are trump, if partner has two keycards and the trump queen, he will bid 5♠; will you be too high?

When diamonds are trump, if partner has two keys and that isn’t enough, you’re in trouble.

When clubs are trump, playing 1430, if you aren’t going to be able to say yes to zero or three keys, do not bid RKC.

When clubs are trump, playing 0314, if you aren’t going to be able to say yes to one key, do not bid RKC.

The purpose of RKC is to keep you out of bad slams, not to find chancy ones. Use control-bidding to find a custom-fit slam; then you might be able to bid RKC knowing you can interpret the answer correctly.

What To Do After A 14 or 03 Response

After your partner answers 14 or 03, and if you need it to be the higher number, bid five of trumps. If your partner has 4 or 3 respectively, they bid the slam.

The Queen Ask

If the next suit above the RKC response is below trumps, it is possible to bid that suit to ask for the trump Queen. Responder bids 5 of the trump suit to deny the trump queen, or else bids six of an outside suit below trumps in which he has a King, or 5N to show no outside King below trumps. Bidding six of trumps shows an outside King in a suit above trumps.

Asking For Kings

Asking for Kings promises that the partners hold all five keycards. To ask for Kings, the RKC bidder bids 5N. Responder bids the number of Kings not counting the trump King, using 6♣ is none, 6♦ is 1, and so on.

An alternate by agreement, called “Specific Kings”, is to show your lowest King by bidding that suit if it is below trump. If it is impossible to show a king because it is above 6 of your trump suit. you should either make an impossible bid (e.g., show a king you have denied earlier in the auction) or just bid 6 of your suit.

Responder has the right to just bid the grand slam if he can tell he has “the right stuff”.

Dealing With Interference

Rarely, your Ace-asking bid may be interfered with. If the opponents overcall 4N in a suit, you can use a convention called DOPI, which stands for “double zero, pass one”. That allows you to give these more negative bids cheaply. In both cases the first available suit becomes your corresponding next higher-level response. It is easiest to be consistent. For example, playing RKC 1430, with diamonds as trump, after 4N - (5♥),

  • Double is one or 4 keycards;

  • Pass is zero or 3 keycards;

  • 5♠ is two keycards, no Q♦;

  • 4N is two keycards with the Q♦, or a known 10 diamonds.

Similarly, after a 4N - (X), ROPI stands for “redouble zero, pass one”.

Note that when the opponent doubles your response to an Ace-asking bid, such as 4N - (pass) - 5♦ - (X), this is normally lead-directing, not penalty, because it is a double of an artificial bid.


When no suit has been agreed upon, and we have bid notrump, 4♣ is the Gerber Convention, asking for Aces. This is true even if the bidder has bid clubs. The replies are:

  • 4♦ No Aces or Four Aces

  • 4♥ One Ace

  • 4♠ Two Aces

  • 4N Three Aces


The standard is that 4♣ is Gerber only when it is a jump over 1N or 2N. You and your partner might agree on other circumstances. Insane people have been known to play “Always Gerber”.

A good agreement for “Is that Gerber?” is to ask if 4N is Ace- or Keycard-asking. If it is not, then 4♣ is Gerber. If it is, 4♣ is not Gerber. There is no point to having two bids that mean almost the same thing.

Control Bidding

Control bids are slam tries, bid for the purpose of understanding where the partnership may have issues preventing a slam or RKC bid. For purposes of this discussion, we assume that a major suit has been agreed trump in a game-forcing auction. While control bids can be used with minors and with Two Over One, you will have to agree on what three-level bids show controls. In a minor one is more often looking for 3N.

A control bid, formerly called a cue bid when referring to slam tries, is a bid that shows the ability to prevent two fast losers in a suit, such as holding an Ace or a void. Most control bids are at the four level or higher. Control-bids are not jump bids. That piece of knowledge helps you avoid confusing splinters and control-bids.

  • Aces and voids are called first-round controls.

  • Kings and singletons are second-round controls.

The standard method of bidding controls is to only bid first round controls, unless we are already known to possess a first round control in that suit, in which case bidding the suit shows a second round control. (See Italian Control Bidding for a better method in which control bids show first- or second-round controls).

  • The first control bid in a side suit shows a first round control (Ace or void) in the suit bid, and denies a control in any bypassed suit. Controls are bid up the line, in other words.

  • If your partner skips over a suit or suits, continuing to control-bid promises a control in the skipped suit(s).

Nothing stops you from cue bidding below the game level and then asking for Aces. For example, 1♥ - 3♥ - 4♦ - 4N. Here, the 4♦ bid showed a first-round control in diamonds and denied holding one in clubs. 4N is RKC, but the bidder is aware of the possible issue in clubs. Instead of 4N, a bid of 5♣ would show that control and deny one in spades. Indeed, suppose responder had xx in diamonds. Normally he could not bid 4N – but knowing diamonds are not going to produce two fast losers, 4N may become possible.

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Slam In The Hand?

Recall this important admonition: Blackwood and RKC are tools for avoiding bad slams, not for finding them. Previously we met The Hand and learned how to start to bid when East or West was Dealer.

West           East
♠K862          ♠AQ
♥AKJ95         ♥T632
♦T5            ♦AKQ6
♣KJ            ♣964

We saw that the correct auction with East the Dealer, using the bids for a 5-4 in the major reply, is:

West   East
--     1N
2♣     2♥
3♠!    4♦

where West made a power raise and East then showed a diamond control but not a club control. Since East opened 1N, that can’t be shortness so East has the A♦ but not the A♣.

Note that West has a worthless doubleton diamond and without the 4♦ bid could not ask for keycards. If West asked and East had as much as two with the Queen, we’d have all but one keycard and bid 6♥. But if the two were the A♠ and the A♣ we might have two diamond losers.

As it is, if we ask with 4N, the reply is 5♥, two without the Queen. We are missing an Ace and the Queen of trump. That’s too much – if we are missing just one keycard but have the Queen of trump, that’s a 6♥ bid. As it is, we just pass 5♥. The 1N system did its job very well, this is not a good slam, about 25%. This hand is a perfect example of this admonition:

If West had been the dealer, after 1♥ - 2N! - 3N! - 4♦(control), we would get to the same place.