E/EW		♠	A Q J
		♥	8 2
		♦	K J 10 6
		♣	6 5 4 3
		♠	6 5
		♥	A 7 6
		♦	Q 9 8 5 4
		♣	A K Q

West leads the ♠2, third or fifth best (so West has an odd number of spades). How should South play (a) at IMP-scoring (team match) and (b) at MP-scoring ('pairs')? 

Declarer counts five top tricks: the ♠A, the ♥A and the ♣AKQ. It is no problem to develop four more in diamonds, totalling nine. The only danger is that the opponents take five tricks before declarer can cash nine…

E/EW		♠	A Q J
		♥	8 2
		♦	K J 10 6
		♣	6 5 4 3
♠	10 8 7 3 2			♠	K 9 4
♥	10 5 4 3			♥	K Q J 9
♦	A 2			♦	7 3
♣	8 7			♣	J 10 9 2
		♠	6 5
		♥	A 7 6
		♦	Q 9 8 5 4
		♣	A K Q

At IMP-scoring this is a clear-cut case. South should not risk the spade finesse at trick one, since if it fails and East switches to a heart, declarer is defeated. So South wins the lead with the ♠A and clears the diamond suit, in order to score at least nine tricks with certainty. After all, the ♠QJ constitute another spade guard.

At MP-scoring this is a lot more complicated and it is far from clear what declarer should do. Giving up on (an) overtrick(s) can be very expensive. Can, because even that is not certain. Whatever declarer does, his score also depends on what other declares ('the field') do. That is what makes it so difficult to take decisions in MP-play.
Possibility 1: Most declarers finesse at trick one, eager to score one, two or even three (clubs 3-3) overtricks. The risk of going down is limited, since West will normally have led from a long spade suit. He shows an odd number, this will usually be a five-card suit. In that case the chance is ⁵/₈ that he has the ♠K. Furthermore: if the finesse fails, it is far from certain that East will switch to a heart. And lastly: if East switches, South will duck twice, hoping for West to have three hearts at most and the ♦A (it will be clear why...).
- At the given layout these declarers will be defeated if East finds the heart switch. Their score will not be disastrous; after all we assumed most declarers were to finesse. A score a bit below average is to be expected therefore.
- If the spade finesse at trick one had succeeded, these declarers would have scored a bit above average.
Conclusion: 'playing with the field' (do what most fellow-declarers in the same situation do) results in non-extreme scores.
- A declarer who refuses the finesse (we're still assuming most declarers will finesse), gambles: in the given layout he will score close to a top, but if the ♠K had been with West, he would score close to a bottom.
Possibility 2: Most declarers do not finesse at trick 1. A non-finessing declarer thus 'plays with the field': if the ♠K is wrong he will score a bit above average, if the ♠K is with West he will score a bit below average.
Now the declarer who finesses is the gambler: he will score a near top if the ♠K is right and a near bottom if the ♠K is wrong.

Two important questions remain:
1. What will the field do?
Experience shows that clearly more than half of the field tends to finesse in fifty-fifty situations.
In this case finessing is probably best, since if the finesse fails declarer still has a reasonable chance of a tie (nine tricks) with non-finessing declarers (i.e. if either East fails to switch to a heart or has five hearts, West has the ♦A and the club suit is not 3-3).
2. Should declarer play with the field or not?
The answer is: that depends...
A declarer who has scored badly so far will be inclined to gamble: a top is useful for him, an average score doesn't help him much.
A declarer who is doing well, usually does best by playing with the field.
Of course we assume he has a clue about what the field will do (it is very well possible that many declarers play a different contract — another aspect that affects his decision)...

Finally: also the opponents' agreements on opening leads play an important part.
- Suppose West had led the ♠8 and EW play 'attitude'-leads: even playing MP-pairs South should not finesse then.
- After a ♠2 'attitude' lead, finessing is the logical thing to do, but even then South cannot be sure: many pairs lead the lowest from five spades to the ten...

Experienced players are often heard to say about MP-play: 'It's a funny sort of game.' This article will have made clear what they mean...