[arepo24]

Often I have noticed a player opening a lead of a singleton K.
I am confused as to why this would be a good lead.
When I have not done that, I have sometimes won the K. Why would I just give it up to an Ace?

[LBengtsson]

The only time where it might be a good or useful lead is where partner has bid the suit, otherwise I would not even consider it, as you say.

[smerriman]

Perhaps you've been watching robots rather than people

[harikannan]

Perhaps you feel the ace is on your left and got Ax or Axx in trumps to gain the lead, put partner in for a ruff.

[undoubling]

arepo24, on 2022-December-16, 20:39, said:

Often I have noticed a player opening a lead of a singleton K.
I am confused as to why this would be a good lead.
When I have not done that, I have sometimes won the K. Why would I just give it up to an Ace?

1) You have a "trump stack" AND an entry to partners hand for ruffs.
2) You expect partner to have values in the led suit and want to "get out of the way" early
3) You "hope" declarer will read you for KQ (?) or longer and will try to ruff losers early
1&2 are "good" ideas but better if the singleton is a low card and NOT an honor
3 is "usually" wishful thinking and can be considered a "desperation" lead that is least likely to cost a trick for your side

[bluenikki]

LBengtsson, on 2022-December-16, 21:57, said:

The only time where it might be a good or useful lead is where partner has bid the suit, otherwise I would not even consider it, as you say.

Contrariwise, if the player on your right has pre-empted and the player on the left has not led the suit, he is marked with the singleton king. Or a void, of course.

[dsLawsd]

Suspicious unless you have the rare hand with a trump stack where partner has shown some values.

[pilowsky]

Bird and Anthias (Winning suit contract leads) show - double-dummy at least - that leading a singleton including kings is best against any major suit game contract.
Which is probably why the robots (and people like me who learned Bridge from robots) lead them.