OD1P - Aug 11 Problem / Solution

HolIgor: The same tesuji could be found in the Ugly sagari. I called it "ugly sagari tesuji". It is a tesuji to consider each time you have two enemy stones cut off like this.

Let's try this?  

Or this?  

After Black 1, White is short of liberties.  

Ko  

How can a failure diagram be in the solution? Unless of course ko is the solution JoeSeki

 

Black cannot resist by capturing at 5 instead of 3.

Black is dead