Hail Mary pass

noun2

1. •
   A long forward pass with little chance of completion, typically used by the losing team when time is running out and no other play is practical, in a desperate attempt to score the winning points.

   • With 11:04 left in the game, and a comfortable 38–14 lead, Smith heaved a 62-yard, Hail Mary pass to Carter. — 1983
2. •
   An act done in desperation, with only a very small chance of success.