Snatched defeat from the jaws of victory 

The act of failing or losing when it seemed a sure thing you had it made.

Dude 1: "Remember that one UFC fight with the Sumo wrestler and the little French guy? Sumo was squeezing the shit outta Frenchy! I thought his head was gonna pop!"

Dude 2: "Yeah, then the little guy squirted a punch 'tween fat bastard's moobs and totally busted his nose. Ref called a TKO."

Dude 1: Fatty totally snatched defeat from the jaws of victory, there.

Snatched defeat from the jaws of victory by Bructus August 13, 2010