4th Suit Forcing
  this page was last updated: 15-June-2008
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Fourth Suit Forcing

  When you and your partner have bid three suits, then it is not often that you will have a fit in the 4th suit. So the use of this 4th suit bid is often artificial. In all of the examples we assume no interfering bidding.  

Consider the sequence: 1 - 1 - 2 - 2 ..?

Now it is possible that responder has a suit (perhaps he's got 5 's and 4 's) but it's unlikely that 's is going to be the final strain. So this 4 th suit is used artificially and asks partner to describe his hand further.

  Now exactly what do we mean by ‘describing one's hand further'?  
  It is generally accepted that partner should show: -  

A stop in the 4th suit (in case No Trump ends up as the final contract).

  (b) More length in one of his own suits than he has already shown.
  (c) Some sort of support for partner's suit(s).
  And what is the more important feature to show? It is generally accepted that showing a stopper (by bidding NoTrump) is the highest priority. Without a stopper then one has to choose the most suitable between (b) and (c).  
  Occasionally you may have no sensible bid and have to ‘lie', but you should never lie about a NoTrump stopper.  
Hand A Hand B So you are opener and have the above auction
        1 - 1 - 2 - 2 ..?
9 9 Partner's 2 bid is 4th suit forcing, what do you bid?
K4 642

Now both of these hands are rather weak (but totally acceptable) openers, but one thing that you can never do is pass a 4th suit forcing bid! So you have to find a bid.

Q9653 KQ65
  With Hand A it's easy, bid 2NT – you have a stop.  
  With Hand B it's not so nice. You cannot bid 2NT with no stop, that is most definitely a no-no. So you actually have no decent bid. You cannot really support partner's 's with a singleton and to bid a minor would show greater length. Still, you have to bid and so with Hand B it's really a toss up between 3 and 3. But these ‘impossible' hand really are the exception and it's usually fairly obvious what to bid.  
Hand C Hand D We'll stick with the same auction here, 1 - 1 - 2 - 2 ..?

With Hand C it's 3 , showing no stop and implying 5-5 (maybe 6-5 but possibly just 5-4 as above) in the minors.

9 K9
64 64

With Hand D you again have no stop but Kx is sufficient support for partner in this situation, so bid 2.

KQ965 KQ65  
Hand E Hand F

And sometimes you are in the fortunate position of having a choice of reasonable bids. Same auction, 1 - 1 - 2 - 2 ..?

K9 9

With Hand E you could have opened 1NT, but suppose you preferred 1 (maybe you're playing a weak NT). Then after partner's 2 4th suit bid you have support for partner and a stop. Bid 2NT - having a stop always takes priority. And it's much the same with Hand F. Show the stop with 2NT rather than the 6th with 3.

K4 K4
AQJ54 AQJ1054
K965 QJ65
  Now 4th suit forcing may be used for many different reasons and in many different situations. So let's have a few examples of 4th suit forcing in action: -  
1. Looking for No Trump.
West East West   East      
                (1) 4 th suit forcing.
AK1076 82 1   2   (2) I have a stop.
KJ72 AQ 2   3 (1)    
K5 9642 3NT (2) pass      
53 AK764            
2. Setting up a game force.
  Now opinion is divided as to whether 4th suit forcing is forcing for one bid, one round or to game. Many established pairs have sorted this out for all situations. My advice to any but the most experienced of established partnerships is to say that 4th suit is game forcing when bid by an unlimited hand – that really does make life so much easier in many situations.  
West East West   East      
                (1) 4th suit forcing.
A1076 832 1   1   (2) I have a stop.
K2 AQ10864 1   2 (1) (3)

Fine, but I really just want to make a forcing 3 bid.

J654 A2 2NT (2) 3 (3)  
AQ3 K7 etc...          
  Here 3 at (1) would have just been (highly) invitational. In situations like this you can use the 4th suit so that your subsequent bid is forcing. This is one of the benefits in using 4th suit as game forcing.  
3. 4th suit by opener.
West East West   East      
                (1) 4th suit forcing.
5 A109862 1   1   (2) I have a stop.
762 K4 2   2      
AQJ4 K2 3 (1) 3NT (2)    
AKQ65 742 pass          
  Let's have a recent example from the club where opener and responder both used 4th suit forcing at different tables on the same board: -  
  Board 16 from Wednesday 14 th Dec, 2005
Dealer: AKQ104 Table A      
West 962 West North East South
E-W vul 1095 pass pass pass 1
  63 pass 1 pass 2
      pass 2♥ (1) pass 3
J93 8652 pass 3♠ (2) pass 4 (3)
A1087 KQJ3        
8743 K6 Table B      
85 974 West North East South
              pass pass pass 1
  7 pass 1♠ pass 2
  54 pass 2♠ (1) pass 3 (4)
  AQJ2 pass 3♠ (5) pass 4
  AKQJ102 pass 4♠ (6)    
Table A: (1) 4th suit forcing. North was unsure if 2 was forcing here and so understandably chose the 4th suit.

This is now forcing, having invoked the 4th suit.


South knows that North has five decent 's and no stop and so he wisely goes for the game.

Table B: (1) This N-S pair do actually have an agreement here. They play Lebensohl with a weak hand after partner's reverse and had agreed that 2 is forcing. However, that may not be the best treatment – maybe it's better to play 2 as the weak bid and go via Lebensohl with an invitational hand. Anyway, that's not the topic under discussion here - see the link.
  (4) 4th suit forcing (asking for a stop).
  (5) Don't have one (a stop) but I have good 's.
  (6) Well… I was North, and I won't bid 5 of a minor if 4 of a major looks viable!
  And what happened? 4 +1 was a complete top.  
Time for a fiasco Board 23 from Friday 16 th Dec, 2005
  I'll go into 1 - 1 - 1 - 1 soon, but just look at this farcical sequence from news-sheet 163:  
West East West   East      
                (1) 4th suit forcing???.
Q109 AK4 1   1   (2) 12-14, (and I have a stop?) .
J854 K1063 1   1 (1) (3) meant as Blackwood but 4NT in this sequence is quantitative and 4 is Gerber.
AK2 10985 1NT (2) 4NT (3)  
Q85 AK pass        
  Clearly comical, and we will address 4 th suit after 1 - 1 - 1 next.  
4. 4th suit after 1 - 1 - 1
  Expert opinion is divided here.  
(a) Some say that 1 is 4th suit forcing.
(b) Some say that 2 is 4th suit forcing.
(c) Some say that 1 is forcing and may be either natural or 4th suit (it's obviously forcing whatever) and what it was will hopefully be clarified later.
  So which treatment is best? Actually I am quite happy playing any of them - as long as you/partner agree!!  
Hand F So let's look at this previous East hand and assume that West's opening was sound and that you are happy responding 1 to the 1 opening.
AK4 How should this hand proceed after 1 - 1 - 1 ?
K1063 (a)

If 1 is 4th suit forcing, bid that followed by a bid at the lowest level next go, assuming you agree with my recommendation that 4th suit forcing is game forcing.

AK (b)

If 1 is natural and 2 is 4th suit, then bid 2 followed by 3 next go.


If 1 is either natural or 4th suit forcing, then bid 1 followed by a jump in 's next go – this clarifies that 1 was 4th suit and that you have a super hand in support of 's.

5. 4th suit forcing followed by a No Trump bid.
  One of the main uses of 4th suit forcing is to establish if partner has a stop for NoTrump. So what does it mean when somebody bids 4th suit and then bids No Trump when partner denies a stop?  
  It generally means that the 4th suit bidder has just one stop and suggests that partner may remove to another spot if he thinks that there may not be 9 quick tricks available in NoTrump: -  
  Example 5.1  
West East West   East      
                (1) 4th suit forcing.
7 AQJ6 1   1   (2) no stop .
75 A64 2   2 (1) (3) I have just one stop.
AK654 872 3 (2) 3NT (3) (4)

Then let's go for it, one of the minors hopefully runs?

AK654 Q72 pass (4)      
  Example 5.2  
West East West   East      
                (1) 4th suit forcing.
K AQJ6 1   1   (2) no stop.
5 A64 2   2 (1) (3) I have just one stop.
AJ9654 872 3 (2) 3NT (3) (4) I don't think one stop is enough.
AJ654 Q72 4 (4) 5 (5) (5)

Fast arrival. 4 would show slam interest if you play 4th suit forcing as game forcing.

6. When 4th suit forcing is not game forcing.
  If a player has limited his hand and then bids the 4th suit he is showing a maximum for his bidding so far but it is not game forcing: -  
West East West   East      
94 AQ1085 1   1      
92 843 2 (1) 2      
AKJ82 964 2 (2) 2      
AKJ8 64 pass          

This West hand is not good enough for 3 at (1) and 2 is correct (the West hand is actually from news-sheet 195 when the holder did bid 3 and they got uncomfortably high - with a different East hand). Thus 2 at (2) defines this West hand pretty well, looking for game if East has a suitable maximum. East has no stop and no game interest and they end up in a good spot. If East had only 4 's then he would have signed off in 3.

  That's it for now folks. I may (almost certainly will) expand on this section in the future if I get any suggestions or more interesting material. So keep in touch.  
  For further reading: -  
  Fourth suit forcing - Max Hardy  
  Pattaya Bridge Club - www.pattayabridge.com
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