If the Baltimore Colts had not lost to the New York Jets in Super Bowl III, this season's New England Patriots probably would be all alone in chasing undefeated glory.
That's because the seeds of the NFL's only unbeaten team in the Super Bowl era - the 1972 Miami Dolphins - were sown in the Colts' stunning 16-7 loss in that January 1969 title game.
Thirty-nine years ago, the Colts' collapse in that championship meeting created a rift between the club's owner and coach, one that festered another year until Don Shula left town.
Shula went to Miami and built the Dolphins' dynasty, topped by the '72 club that finished 17-0, beating the Washington Redskins in the Super Bowl.
And all because of a Baltimore loss that stuck in owner Carroll Rosenbloom's craw.
"When you look back on your life and the directions it takes and the decisions that are made, it's amazing how things unfold," said Shula, 78, the winningest coach in NFL history.
"After Super Bowl III, my relationship with Rosenbloom was not very pleasant. I loved Baltimore - the people, the fans and everything that Colts football stood for. But Rosenbloom's New York buddies never let him forget [the heavily favored Colts' loss], and he never let me forget it.
"If we had won that game, and continued to win, I certainly wouldn't have gone. I'd still be in Baltimore, eating crab cakes."
In his last season with the Colts, before he left town, Shula gathered the pieces from that disappointing loss and added to the legacy that would land him in the Pro Football Hall of Fame.
"When Shula lost the Super Bowl, his job was pretty much gone," said Bobby Boyd, then an All-Pro defensive back for the Colts. Nonetheless, despite Rosenbloom's sniping, Shula went to work, determined to toughen the defense made penetrable by the Jets' short-passing attack.
"[Jets quarterback] Joe Namath had nitpicked us to death throwing underneath our coverage," said Boyd, who became a Colts assistant coach after the Super Bowl. His third day there, Boyd was summoned to Shula's office.
"We need a strategy to combat the short stuff," Shula said.
For three hours, the two men worked, devising a plan that broke the mold of traditional zone coverage and establishing a template for defending the revved-up passing games of today.
The Colts called it the double zone, a scheme whose purpose was to take away the short game. It now is called the cover-2, and its primary function is to shut down long passes.
Different names, different purposes, but still basically the same defense.
The Colts had the cornerbacks and linebackers combine to defend against short passes, while dropping the two safeties to guard against the bomb.
Gradually, the double zone worked its way into Baltimore's game plan. Shula gave it a trial run in 1969. When he left the Colts, the double zone became a favorite of Shula's successor, Don McCafferty, who rode it clear to a Super Bowl victory in January 1971.
"In my opinion, we won Super Bowl V because of that defense," Boyd said. "Nobody else in the league was using it. Teams didn't know how to attack it."
Shula, of course, took the scheme with him to Miami, winning consecutive Super Bowls in 1973 and '74.
Those Dolphins teams were led by quarterback Bob Griese. However, the starter during much of Miami's undefeated 1972 season was a player familiar to Colts fans - Earl Morrall.
In 1968, Morrall started the entire season for the Colts, including the Super Bowl loss, for an injured John Unitas, who had healed enough to play by the title game. After a horrid first half, Shula benched Morrall for Unitas, who led the Colts to their only touchdown.
In 1972, Morrall came off the bench again, starting 11 games for the injured Griese. But unlike with the Colts, Shula reinstated his mainstay (Griese) for the Super Bowl.
Had Shula learned from his earlier Super Bowl loss?
"Different circumstances," he said. "Griese was my quarterback of the future and he was healthy; John was on the downside of his career - and still hurting."
However, several Colts who were there contend that Shula wised up after Super Bowl III.
"I think Shula learned a lesson in that game," said Dan Sullivan, an offensive guard. "In 1972, he must have thought, 'It'll be hard to bench Morrall, who won 80 percent of our games ... but I'm going to go with my No. 1 guy, though he's a little rusty.' "
With Miami, Shula had no intention of reliving the past, halfback Tom Matte said.
"In Super Bowl III, Shula learned he didn't put [Unitas] in fast enough," Matte said. "If you're behind, you put your team leader in there and there's a change in attitude.
"When John comes in, the defense gets worried and the offense says, 'Oh boy, the Holy Grail is in the huddle.' "