Suppose you are the declarer and you need to hold this suit to 1 loser:
Dummy: Q 6 4 2
Declarer: K 7 5 3
Looks fairly hopeless, right? Most of the time (probably 80% or so) you will lose 2 tricks in this suit. Your only chances to hold it to one loser are:
- Delay playing the suit so that one of the opponents makes a costly discard in it; or
- Find one of the hands with a doubleton Ace (and guess which one).
Suppose you think LHO is more likely to hold the Ace doubleton. Perhaps they made a takeout double of this suit. Lead to the Queen in dummy. If it wins, lead back toward your hand and duck. If the now bare Ace wins, you look like a hero to your admiring partner. If it doesn’t, oh well, nothing was going to work.