East-West vulnerable.  
South deals.
                              North
                              S: K Q J 7          
                              H: 10 4 3      
                              D: 9 8 6 5     
                              C: 6 3     
            West                             East
            S: 10 9 4                        S: 5 3 2        
            H: 9 7 5 2                       H: 6          
            D: K Q 10 4                      D: A J 7 3 2         
            C: A 7                           C: J 10 9 5    
                              South                         
                              S: A 8 6
                              H: A K Q J 8  
                              D: Void      
                              C: K Q 8 4 2
          The Bidding:  
                  South    West    North    East                  
                   1H      Pass     1S      Pass
                   3C      Pass     3H      Pass
                   4D      Pass     4H   (All Pass)
          Opening lead: DK
     This hand presents an interesting problem at matchpoints. 
While four hearts is the normal contract, and ten tricks should
be available with careful play, four spades is the best contract
and, in fact, as the cards sit, six spades cannot be defeated.
     In four hearts, South must trump the opening lead and then
lead the king of clubs.  He cannot come to ten tricks without
knocking out the ace of clubs.  West wins and returns another
diamond and South finds himself with a 3-3 trump fit.  If the
outstanding hearts do not divide 3-2 he is going to be wide open
in diamonds.  He can counter this by trumping the diamond,
cashing the club queen and the spade ace.  Crossing to dummy with
a spade to trump a third diamond, Cashing the ace and king of
hearts. Playing a third spade to the dummy to cash the ten of
hearts, And then playing the last spade from dummy.  West will
trump this trick and play a diamond but declarer will come to
three diamond ruffs, three trump tricks, three spades and a club.
     In four spades from the North, East could lead the ace of
diamonds.  This can be trumped in the South hand with a small
spade.  The king of clubs is next and the best that West can do
is win the ace and play another diamond.  This trick is trumped
in dummy and the ace of spades is cashed.  The closed hand is
entered with the ten of hearts.  Two more rounds of trump draw
all the outstanding spades.  If spades were 4-2 there is still a
high spade in the closed hand to take care of that as well.  At
this point, all that will be left in the South had will be the
four top hearts which will take the balance of the tricks.
     Of course, if East selects the singleton heart as the 
opening lead declarer has a more difficult time coming to 
twelve tricks but eleven should be a common result.