Ace from Ace-King

Ace from Ace-King refers to the lead of the ace when holding A-K-x or longer. Playing standard leads, ambiguity occurs when partner leads a king because he might hold A-K-x or K-Q-x. Leading the ace from A-K-x distinguishes these two scenarios.

The ace lead creates a new ambiguity - is it from A-K-x or A-x-x? - but this is theoretically less common since players often avoid leading an unsupported ace at trick one.

If playing Ace from Ace-King, you should lead the king from an A-K doubleton. (This is the opposite of standard leads, in which the ace is led.) Leading the king followed by the ace tells partner that you have a doubleton (and may be able to ruff the third round of the suit).