[mike777]

In a top level event you have decided a passive or aggressive lead is called for.

1. What was your general thought process to arrive at that conclusion? NT vs suit contracts, partscores vs games?


2. How would you generally describe a passive or aggressive lead to your nonexpert partner.

[DavidKok]

I wrote the following two months ago in a DM, so I'm copying it here even though it only partially addresses the question (and I wrote it as a single paragraph in a long context):



In general, deciding whether to be passive or active is probably the most important inference to draw from the auction. Passive defence profits from a simple logical truth: if a suit is going to be played anyway, it is advantageous to play 2nd and 4th to the trick, rather than 1st and 3rd. But the condition, 'if it is going to be played anyway', is often not met. We have to take a view on whether we need to play a suit ourselves, even at risk of giving declarer unearned tricks in the suit, just to get our own tricks there. If an honour in a suit is going to come in eventually anyway, no need to play that suit.
This is crucial for the lead. If the opponents have no great fit, or have shown relatively balanced hands, or if the balance of strength is very close so any trick given up might be the critical one, passive defence can be attractive. Conversely, if the opponents are likely to make the contact eventually if left to their own devices, we have to risk giving up overtricks or making life easy for them just to get some chance of setting the contract in return. To me this is vital in almost all defensive situations.
If passive defence is called for, leading empty suits is good, leading away from honours is bad, and we should on balance lean towards playing suits where we are least likely to give something away.
If active defence is called for, leading suits with honours in them is good, leading empty suits is bad, and we should on balance lean towards playing suits where we are most likely to establish tricks.
These are almost direct opposites (though leading from a sequence, especially a 3-card sequence or longer, is good for both).
Some additional rules of thumb: be passive against partscores, after invitational sequences, against grand slams and on auctions where the opponents are likely in only an 8-card fit with no second suit fit. Conversely, be active against games after a slam try, against small slams, against suit contracts on competitive auctions and against freely bid 4M games.



A topic omitted from this cut (but very relevant) is how to combine inferences from the auction with inferences from the cards in your hand. The above only paints an incomplete picture, emphasising the auction.

[mikeh]

I agree with David but would add that leading at mps and leading at imps are two (sometimes very) different matters. That’s because priorities are usually different.

I’ll leave aside lead issues when we are confident of a plus and are wishing to maximize that plus…as may happen if we’re defending a sacrifice. When the opps have reached a contract that they have bid with the apparent intent of going plus, we may need to be aggressive if we are to have a chance of beating it. But aggression carries with it the risk of giving away a trick on opening lead.

At mps there are often hands on which we appear to have little chance of beating the contract. If our lead leads to -450 as opposed to -420 this is the mp equivalent of our lead resulting in -420 when a passive lead would have led to +50.

At mps we want to hold the opps to the tricks to which they are entitled and we do not want to give them anything more. At imps we want to beat their contract and we don’t much care about leaking an overtrick.

How these differences play out in real life isn’t always dramatically different. Our hand and the auction may combine to make us think that their contract is virtually cold. In that case we should go passive even at imps since aggression will more often than not cost an imp and the chances of winning, say, 10 imps (when the aggressive lead results in beating the contract) seem vanishingly low. But it’s very important to understand what one is trying to do….beat the contract or avoid giving away a trck on opening lead.

It’s actually the flip side of declarer’s priorities. At mps one sometimes prioritizes taking as many tricks as possible while at imps one tries to take the safest line to make the contract, little caring that doing so might mean giving up on a good chance for an overtrick.