Definition of "undoing"

So far as the ape was concerned, Sabor reasoned correctly. The little fellow crouched trembling just an instant, but that instant was quite long enough to prove his undoing.

1912 October, Edgar Rice Burroughs, “Tarzan of the Apes”, in The All-Story, New York, N.Y.: Frank A. Munsey Co.; republished as chapter 5, in Tarzan of the Apes, New York, N.Y.: A. L. Burt Company, 1914 June,

The extra 30 minutes could not separate the sides and led to a nerve-shredding finale that has so often been England's undoing, with a dismal record of just one win in seven shootouts at major tournaments before this.

2018 July 3, Phil McNulty, “Colombia 1 - 1 England”, in BBC Sport‎