Can you believe it? Fifty years ago this weekend, Joe Willie Namath allegedly “guaranteed” that a prohibitive underdog football team would win the biggest game of the year, the Super Bowl.

As it turned out, the New York Jets did win that game, 16-7 against the Baltimore Colts. The date was Jan. 12, 1969.

One aspect made this game among the most memorable in pro football history.

It was the first victory of an American Football League team over a team from the supposedly “superior” National Football League. The AFL and NFL had brokered a merger after the two leagues battled over draft picks out of college. The merger took effect the season after the Jets-Colts Super Bowl III game. Three NFL teams — the Colts, Cleveland Browns and Pittsburgh Steelers — moved into what became the American Football Conference, which competed with the National Football Conference in the newly reconstituted NFL.

The AFL had come into being in 1960. The new league proved to be an entertaining venture for football fans. I was one of them as a youngster. I followed the AFL closely during its early years, cheering the exploits of Daryle Lamonica, John Hadl, Len Dawson, Cookie Gilchrist, Paul Lowe, Keith Lincoln, Lance Alworth and, oh my . . . I could go on. But I won’t.

The AFL then landed a prize rookie out of Alabama named Joe Namath. The flashy quarterback became an instant celebrity. He signed a $400,000 contract with the New York Jets.

The leagues met in two prior Super Bowls. The Green Bay Packers defeated in order the Kansas City Chiefs (35-10) in 1967 and the Oakland Raiders (33-14) in 1968.

Then came Super Bowl III. The Colts were favored by nearly three touchdowns over the Jets. Namath wasn’t hearing that. He made some kind of semi-flippant remark to reporters that many of them interpreted as a “guarantee” that the Jets would win.

Then they did. They manhandled the Colts. The AFL had gained “parity” with the NFL.

And Joe Namath had just written his ticket to the Pro Football Hall of Fame in Canton, Ohio.

Allow me this bit of heresy, which is that Namath’s role in defeating the Colts is the only reason he is enshrined in the Hall of Fame in the first place. His career was otherwise, shall we say, not exactly sparkling. I won’t debate the issue here, except that one game can enable someone to gain athletic immortality.

Joe Namath did on that day 50 years ago. Man, some of us are getting old.