Posted 2018-August-31, 02:54
It may be basic for some, but I have never come across this specific problem before. So lets try thinking it through from first principles and put ourselves in partner's seat:
Option 1: You play the Q (consistent with the usual principle of playing the lowest of touching honours, when following suit).
If your partner can read you for a doubleton, then from his/her point of view the Q could be unblocking from a QX holding. With QXX, you would likely play a low card (whichever signals encouragement in your methods).
So partner will probably expect you to hold a singleton or doubleton when you play the Q, but cannot tell whether you hold the king if you also play Q from KQ.
Option 2: You play the K (consistent with the usual principle when holding a touching-honour doubleton and the card that you would play if partner led low and dummy holds only low cards).
You are much less likely to play the king as an unblocking play with KX, since this would promote declarer's queen. The king would seem to be consistent with a singleton or KQ doubleton.
So, yes I am reaching the same conclusion as the other contributors - play the king.