Ten years ago, the New England Patriots were a season removed from a 5-11 record under first-year head coach Bill Belichick. Tom Brady was filling in for injured starting quarterback Drew Bledsoe. A dynasty had not yet flowered in Foxborough, Mass.
The wind-blown, snow-strewn "Tuck Rule" game, that memorable divisional playoff game against the Oakland Raiders on Jan. 19, 2002, changed all that.
"Sometimes to have a run like we had, you need a signature break," said former Patriots linebacker Tedy Bruschi, now an NFL analyst for ESPN. "That game was a historic starting point for us."
Added Brady: "That's the margin of error sometimes when two good teams are playing. It's one call. It's one play. It's one bounce."
What if referee Walt Coleman's fumble call hadn't been reversed by instant replay? What if the Raiders' offense had gotten the ball and run out the clock? How would NFL history have been altered?
"Tom Brady should really be indebted to the Raiders forever; if not to the Raiders, at least to Walt Coleman," former Oakland receiver Tim Brown said. "If not for that reversal, he goes into the offseason as a guy who fumbled the ball away to lose a home playoff game."
An intriguing thought.
"Does Bledsoe come back and assume the starting job?" asked former Raiders cornerback Eric Allen. "How does Brady and Belichick, how does that marriage work?"
A decade later, we have seen that power combo win 124 games -- more than any coach-quarterback tandem in league history. Their shared record is 124-33, a sublime winning percentage of .790.
It is not unreasonable to imagine that if the Raiders had won, they might have followed the Patriots' path, winning at Pittsburgh, then beating the St. Louis Rams in Super Bowl XXXVI.
"We win that game and the first thing that probably happens is, Jon Gruden doesn't get [traded to Tampa Bay]," Allen said.
And that would mean the Raiders' young head coach wouldn't have wound up coaching the Buccaneers the following season in Super Bowl XXXVII -- where they beat the Raiders 48-21.
Those Raiders, it can be argued, might have won two Super Bowls. That would have given owner Al Davis five Super Bowl trophies -- tying the San Francisco 49ers and Dallas Cowboys for the second-highest total -- only one behind the Pittsburgh Steelers.
And what of the Patriots? If they hadn't won the final game of the 2001 season in New Orleans, would they have found the wisdom and confidence and strength to win back-to-back Super Bowls in the 2003 and 2004 seasons?
"I think without that play there would be no Adam Vinatieri kicks or snow angels or going to Pittsburgh, overcoming those odds going up against the St. Louis Rams," former Patriots wide receiver Troy Brown said. "That particular play, man, I think it changed history for both teams.
"It saved our playoff chances and we went on to be world champions."
Then Brown smiled, held up his glittering Super Bowl XXXVI ring and laughed.
Greg Garber covers the NFL for ESPN.com.