Rashard Mendenhall took the handoff with every intention of moving Pittsburgh a little closer to completing an improbable comeback.
Then, a big hit, the ball popped out of Mendenhall's hands, and Desmond Bishop took off with it for the Green Bay Packers.
It would be the biggest mistake on a night filled with them for the Steelers.
Green Bay hoisted the Vince Lombardi Trophy with a 31-25 victory Sunday.
Mendenhall's fumble on the first play of the fourth quarter -- Pittsburgh's third turnover of the game -- helped the Packers hold on after the Steelers attempted to rally from an early 21-3 deficit.
Let's not forget Ben Roethlisberger throwing two interceptions, including a pick that was returned 37 yards for a touchdown by Nick Collins that gave Green Bay a 14-0 lead less than 12 minutes into the game.
The Packers stretched it out to 21-3 before the Steelers made a game of it.
Roethlisberger hooked up with Hines Ward for a touchdown that made it 21-10 at halftime. Mendenhall rumbled into the end zone from 8 yards out to bring Pittsburgh even closer, 21-17.
And, as the final period started, the Steelers had second-and-2 at the Green Bay 33.
Then, the fateful play.
Mendenhall took the handoff, but Clay Matthews drove a shoulder right into the runner and massive Ryan Pickett dived in to complete a 595-pound sandwich.
The result of that fearsome collision: the ball came flying out, and Bishop swooped in to scoop it up.
The Packers drove for the touchdown that provided some breathing room.
The Steelers never quit, scoring one more time to make it uncomfortably close for the Packers as time ran out on the clock, but Green Bay held on the final possession to send the Lombardi Trophy back to Title Town, the home of the coach whose name it bears.