The Steelers were facing fourth-and-10 from their own 40-yard line, and quarterback Terry Bradshaw, under great pressure from Oakland’s pass rush, launched a pass toward running back John "Frenchy’ Fuqua. Oakland linebacker Jack Tatum collided with Fuqua and the ball lurched toward Harris, who picked it off his shoetops and ran for the game-winning score.
The play, called by NBC’s Curt Gowdy and Al DeRogatis, was controversial because it was not clear who touched the ball first. Under the NFL rules at the time, if Fuqua touched the ball first, the play would have been ruled illegal and the Raiders would have taken over on downs. However, if Tatum touched the ball first, the play was legal, and that call was upheld by referee Fred Swearingen and his crew.
That rule was changed in 1978.
Harris’ play gave the Steelers a 12-7 lead, and Roy Gerela’s extra-point clinched a stunning 13-7 victory. It was the first playoff victory in Steelers history.