Source: Mr Bridge by David Huggett
It takes a new player ages to gain the confidence to take a finesse for the first time but, once the habit kicks in, it can become an obsession. Look at the following deal, playing teams or rubber:
3NT looks obvious. West leads the two of spades, bringing good news and bad news. The bad news is that they have found your weakest suit; the good news is that you expect the suit to break 4-3 as they are playing fourth-highest leads. There can be little point in holding up, so you win and play three rounds of diamonds, happy to see the diamond suit break evenly. A count of top tricks reveals that you need only three clubs for your contract. The correct way to do this is to play off the ace and the king; after that, lead low towards the jack if the queen hasn’t appeared. This means that you can cater for queen doubleton offside as in the diagram. If the diamonds had not broken evenly, you would have needed clubs to break 3-3 with the finesse working. The above example was a matter of playing with the odds, but sometimes there are other factors to consider. It may well be that you are anxious to keep one particular hand off lead. This objective might cause you to think twice about finessing. Assume rubber or teams scoring on our next deal.
You are in 3NT. The lead is the five of hearts, which goes to the nine and your jack. It looks like West has all the top hearts, making it your priority to keep East off lead. Again, if you count your winners, you can see that you need only three diamond tricks, not four. This means it must be better to play off the two top diamonds in case the queen is doubleton offside. You do not mind losing a trick if West has Q-x-x.
You are in 4 and win the club lead with your ace. You have two losers in the minors and maybe a spade loser. If you have to lose a spade, you cannot afford to lose a trump. So test the spade suit by playing a spade to the queen.
You take this finesse early because it dictates how you should play the hearts. With now only two losers outside of trumps, you can afford a trump loser. The safety play is to lay down the ace first, not to take the finesse. The singleton king offside means you hold your trump losers to one, while taking the unnecessary finesse would cause you to have two. Of course, if the play of the trump ace draws small cards, you would cross to dummy with a spade and lead towards the queen of hearts. If the spade finesse failed, you would need East to hold king doubleton in trumps.
You arrive in 6 and get a trump lead. With eleven tricks on top, it ought to be clear that the extra trick can come only from hearts. However, if you take two heart finesses early on, you will find the outcome disappointing. You have to take a finesse in hearts it is true — but only at the right time. So draw trumps, play the two top diamonds and ruff a diamond in hand; then play three clubs ending in dummy. Only now, lead a heart to the ten. West wins cheaply but has no safe exit: a heart lead is into your tenace, while anything else gives you a ruff and discard. Either way, you will have ensured your contract.