Where it all began for two football legends

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New England Patriots quarterback Tom Brady, left, and Indianapolis Colts quarterback Peyton Manning shake hands.

Charles Krupa, AP

When the New England Patriots host the Denver Broncos Sunday, it will be the 16th time star quarterbacks Tom Brady and Peyton Manning will play each other.

The two future Hall of Famers have the greatest rivalry in football today, and there's two men who saw their talent early on, CBS News' Elaine Quijano reports.

"My favorite quarterback is definitely Peyton Manning, bar none," athletic director at Fort Worth Day School Frank Gendusa said.

"It's quite simple, Tom Brady is my choice of quarterbacks," former Junipero Serra High School football coach Tom Mackenzie said.

Gendusa was Manning's high school football coach, and Mackenzie coached a teenage Tom Brady.

"He had the size and the physical skills, and he also had the desire, self-discipline and perseverance to become the best possibly he could be," Mackenzie said.

Twenty years later, they are now considered among the best players of all time, a once-in-a-lifetime opportunity for any high-school coach.

"You know, some coaches go through their entire career, and if they are lucky, they'll have a Peyton Manning enter their lives," Gendusa said. "His preparation was always so much better than everyone else. He wanted to watch film extra, he did the extra running, no one outworked him in the weight room. He was just that kind of leader."

Brady, 37 years old, and Manning, 38 years old, both quarterbacks, are now in the peaks of their careers.

They are number two and number three in all time wins. Brady has won three Super Bowls. Manning has one ring and recovered remarkably from three neck surgeries to break the record for most touchdown passes in NFL history.

"You're talking about one of the great rivalries in the history of sports," CBS Sports' Jim Nantz said. "It transcends the NFL."

Contemporaries on the field, they are a study in contrasts off the field.

Manning is known for having an outgoing personality, while Brady is more reserved.

Manning married his college sweetheart, and Brady is married to perhaps the most famous supermodel in the world.

But at the end of the day, the Manning-Brady relationship is equal parts cutthroat competition and mutual admiration.

"Phenomenal player," Brady said about Manning at a press conference Wednesday. "So consistent and durable. We've had a great rivalry."

"So, yeah, I consider Tom a great competitor on the field but then a good friend off the field," Manning said.

"They both are incredibly competitive people," Nantz said. "They want to win this game, but they have great respect for one another, but when this football game takes place on Sunday, there is no one quarterback that the other one wants to beat."

An epic rivalry, but for two coaches, it's simply about the talent that they saw early on.

"As good of a football player as he has been throughout his career, he is a much better person," Mackenzie said.

"There is nothing like it from a coaching standpoint to see one of your players succeed like Peyton has," Gendusa said.

In the 15 games they've played against each other, Brady has won 10 contests.

Manning makes some $12 million off the field. Brady makes about half as much.