After the 2001 NFL season, the Oakland Raiders met the New England Patriots in a divisional playoff game.
The game was played at New England in a driving snowstorm, and Oakland dominated much of the action, carrying a 13-3 lead into the fourth quarter. They still led, 13-10 with time running out, and only had to stop one more New England drive in order to secure victory.
New England, however, and specifically new quarterback Tom Brady were the league’s up and coming media darlings. Oakland, on the other hand, had always been a malcontent franchise, with renegade owner Al Davis continually causing headaches for the league office.
The game appeared to be in the bag for the Raiders when Brady was sacked by Charles Woodson on a cornerback blitz and fumbled the ball. It was recovered by Oakland, and that was all she wrote. The Raiders would run out the clock and advance to the AFC Championship. Except that wasn’t all she wrote.
The referees reviewed the play and cited an obscure rule (Rule 3, Section 21, Article 2, Note 2) that they decided meant that the play wasn’t, in fact, a fumble.
Apparently, even though he clearly wasn’t in the process of attempting a forward pass, Brady was in the process of "tucking" the ball (what exactly constitutes a tuck continues to elude me to this day), and therefore, losing the ball constituted an incomplete forward pass, not a fumble.
Given new life, the Pats proceeded to kick the tying field goal to send the game to overtime, and the winning field goal in the extra session, before going on to win the Super Bowl. All thanks to a tuck.