I guarantee it

Since it is Super Bowl weekend here is a post on Joe Namath and The Third Super Bowl.
Joe believed in himself, he fought against all odds and won.
At the time NO ONE thought he and his team had a chance to win and when his back was up against the wall and people poked at him he held to what he believed in...here is Joe Willie Namath...

The apex of his career was his performance in the Jets' January 1969 16–7 win over the Baltimore Colts in the third World Championship Game, which was before the AFL-NFL merger. Namath was named MVP of Super Bowl III. This win would make him the first quarterback to ever start and win a national championship game in college, and to start and win a major professional league championship and a World Championship.

 The Colts were touted as "the greatest football team in history". Former NFL star and coach Norm Van Brocklin ridiculed the AFL before the game, saying "This will be Namath's first Professional Football game." Writers from NFL cities insisted it would take the AFL several more years to be truly competitive with the NFL. Much of the hype surrounding the game was related to how it would either prove or disprove the proposition that the AFL teams were truly worthy of being allowed to merge with the NFL; the first two such games had resulted in blowout victories for the NFL champion in the two previous years, the Green Bay Packers, and the Colts were even more favored by media figures and handicappers than the Packers had been.

Three days before the game, an intoxicated Namath responded to a heckler in Miami with the now-famous line: "We’re going to win Sunday. I guarantee it." His prediction was initially ignored, but it became legendary after the Jets' upset of the Colts.

In the game, however, Namath backed up his boast and showed that his success against tough American Football League competition had more than prepared him to take on the NFL. The Colts' vaunted defense was unable to contain the Jets' running or passing game, while their ineffective offense gave up four interceptions to the Jets. Namath was the game's MVP, completing eight passes to George Sauer alone, for 133 yards. Namath acquired legendary status for American Football League fans as the symbol of their league's legitimacy.