There have been countless moments in NFL history when the improbable happened, but perhaps the most famous of all examples is the 'Immaculate Reception'.
Voted by NFL Films as the greatest play of all time - as well as the most controversial - the 'Immaculate Reception' resulted in the Pittsburgh Steelers scoring the game-winning touchdown with under 10 seconds left to play.
It occured in the 1971 AFC divisional playoff game against the Oakland Raiders, and was the start of a long rivalry between the two franchises.
A touchdown seemed incredibly unlikely for so many reasons, including the pressure Steelers quarterback Terry Bradshaw was put under by the Raiders defence.
Bradshaw managed to find space to throw, targeting his running back John Fuqua, but Fuqua would never gain possession of the ball.
Instead, in a collision with Raiders safety Jack Tatum, the ball bounced backwards in the direction of Franco Harris, who gathered the ball before it touched the ground before spinting away to score the game winning touchdown.
There has since been plenty of controversy surrounding the play.
NFL rules at the time were such that if the ball had only hit Fuqua and not Tatum then Harris would not have been an eligible receiver for the play.
Many others believe that Harris did not catch the deflected pass before it had hit the ground.
Whether it touched Tatum or the ground is a matter for debate, but what is not is how the 'Immaculate Reception' became a turning point for the Steelers, who would go on to win four Super Bowls before the end of the decade.