A clear and cold late December afternoon in Baltimore's Memorial Stadium. The sun struggled all day to bring the temperature above the freezing mark, and by game time the barometer rests around forty -- a fine football day. The bundled crowds assemble in the face of a light southerly breeze as Johnny Unitas, black high-topped cleats and buzz cut in place, warms up along the sidelines. Baltimore is in a fight for playoff positioning, trailing Miami by half a game in the standings in the regular season's final week. 
The 38-year-old Unitas was nearing the end of an unrivalled career. He had been dueling for starts with Earl Morrall all season, but there was plenty of gas still in the tank.
The previous year marked the merger of the upstart AFL with big-brother NFL. The storied Baltimore franchise had been called to play the low-rent league frequently as a member of the new AFC East. In 1970, they defeated Boston in the first-ever meeting, 27-3, with Unitas throwing 3 touchdowns. In 1971 the Patriots became "New England," but the early results were much the same. Baltimore had walked all over the Patriots in brand new Schaffer Stadium back in October, 23-3. The lone Patriot score was a Charlie Gogolak field goal, courtesy of a 19 yard interception return by Patriots defensive back John Outlaw who picked Earl Morrell in the second quarter.
Here now in December, the 10 - 3 Colts had the Dolphins in their sights and 5 - 8 New England firmly in the rearview. Across the field from Morrall and Unitas, two kids in their early 20's were stretching for the kickoff: a speedy receiver from Stanford named Randy Vataha and his old college quarterback, rookie Jim Plunkett.
The game was an ambush. Playing with nothing on the line, the Patriots sprinted to the lead on the feet of their young guns. Plunkett connected with Vataha from 2 yards out to open the scoring. The Colts answered with a field goal and were driving again, moving across midfield when 3rd year pro Outlaw stepped in front of an errant Unitas offering and raced sixty yards up the field for a touchdown, the longest return of the season.
Coming out after the half, Unitas took his men in on a 31 yard strike to favorite target Eddie Hinton and it looked like the football universe would right itself. But the Patriots bounced right back. Two weeks previous, New England had helped the Colts with an upset victory over Miami, keyed by two Plunkett scoring throws and an interception return for six. The pattern would repeat this week. Plunkett found Vataha for an 88 yard touchdown pass in the fourth quarter to put the game away. Hinton and Johnny U would add one more to make it look better in the books, but the story had already been written. It was New England's first regular season win over an Original Franchise since the merger a year before.
Unitas and Morrell led the Colts through the playoffs with a win over Cleveland before meeting and losing to Miami, whose seeding advantage had Baltimore on the road for that game. Miami had corrected a tie from the first week with a final week win over the Packers. They ultimately lost to the Cowboys in the Super Bowl. Among his many honors, Unitas' 17 years with the Colts is still a team record.
Plunkett earned Rookie of the Year honors, though the team finished 8-6. He helped the Pats to three upset victories that year, leading with an opening day two-TD display against the Raiders to christen Schaffer Stadium. Plunkett would ultimately find himself in Oakland, also finding there the success that eluded both he and the team in New England.
John Outlaw was purged when Coach Fairbanks took over the New England squad, but found a home with the Eagles where he played for five more years.
Randy Vataha played six years with the Pats, ending his career with a one-year stint in Green Bay. After retiring, Vataha helped to found the USFL with an ownership stake in the Boston Breakers.
It would take the Patriots until 1980 to claw their series record with the Colts to .500 parity. In the decades since, New England has widened the split and the series now favors the Pats at 44-28, 2-1 in postseason play. The Colts have won four of the last five, however, including a playoff victory in 2006.
Much has changed in the league and with these franchises since that night in 1971, as the inimitable Johnny U was on his way out and Jim Plunkett on his way in. Goalposts were moved back and out of the way, and the Colts suffered an ignominious removal to Indianapolis, among other things. But just as the 1971 matches revolved around the quarterbacks, it was the rise of the quarterback position that turned these teams from sometime foes to full time rivals.
Peyton Manning was drafted in 1998 out of the University of Tennessee and immediately went to work on the history book, breaking rookie records left and right and throwing the ball all over the league. By the time New England drafted the unlikely Tom Brady in 2000, Manning had thrown for 52 touchdowns and almost 8,000 yards.
In 2001, New England's starting quarterback Drew Bledsoe was leveled against the Jets. Brady stepped in and started the rest of the year, leading the team to a Super Bowl victory. He also began to chip away at Manning's head start, with a 44-3 victory in the their first encounter.
The rest, you know.