Sources say the four-time MVP has instructed agent Tom Condon to negotiate the details of a deal with Denver. Manning became a free agent when the Indianapolis Colts released him March 7 after the quarterback missed all of last season because of multiple neck surgeries.

The addition of Manning could well lead to Denver trading Tim Tebow, even though the popular QB energized the Broncos in leading them to the playoffs last season despite some uneven play.

Manning and the Broncos are negotating a contract that's believed to be a five-year deal for $95 million. Denver Broncos Vice President John Elway and Manning apparently started talking about the contract during Manning's visit to Colorado on March 9. It's also believed the contract would have conditions that would protect the Broncos in case Manning is not healthy enough to play.

One of two other teams considered finalists for in the race to sign Manning, the Tennessee Titans, released a statement Monday saying they were out of the picture.

"I want to thank the whole organization for their efforts in trying to sign Peyton and also to Peyton for the time he put into the process," Titans owner Bud Adams said. "Peyton called me this morning to inform me of his decision and obviously I am disappointed, because I thought we would be a perfect fit."

The San Francisco 49ers were the other team trying to land the star QB.

Manning notified both the 49ers and the Titans of his decision to join the Broncos on Monday.

Manning's apparent move comes less than two weeks after he was cut loose by the Indianapolis Colts, who released him rather than pay a $28 million contract bonus. That was the end of an era, a 14-year alliance between the team that drafted Manning No. 1 overall and the QB who brought Indianapolis from football irrelevance to the 2007 Super Bowl title and a second appearance in the NFL championship game three years later.

But with Manning coming off a series of operations to his neck, the Colts decided it was time to rebuild from top to bottom, and they are expected to take Stanford quarterback Andrew Luck with the top pick in April's draft.

Two days after standing alongside Colts owner Jim Irsay during an emotional farewell news conference on March 7, Manning began his free agency tour in the place it may end: Denver. Manning landed on Tebow's turf with all the trappings of star treatment - flown to town on a chartered plane, then spending the day with Broncos vice president of football operations John Elway, coach John Fox and general manager Brian Xanders.

From there, Manning crisscrossed the country in search of a new team, as various clubs courted a guy with more than 50,000 yards passing, nearly 400 touchdowns and 11 Pro Bowl selections. After Denver, next up was a meeting with the Arizona Cardinals, and he also spent time speaking with - or throwing for - the Titans, 49ers and Miami Dolphins, with TV cameras and even helicopters often on the trail.

Somehow, the 49ers managed to keep their audience with Manning a secret for days, until word emerged that they were in the running for him, too.

In the end, though, Manning is close to trading in his Colts horseshoe helmet for one adorned by a Bronco. The move would allow him to stay in the AFC, a conference he knows well and one considered weaker than the NFC at the moment, and potentially re-establishes the tantalizing prospect of playing against his brother, New York Giants quarterback Eli, in a Super Bowl. They already have three titles in the family.

As it happens, the next Super Bowl will be hosted by New Orleans, which also is be the Mannings' hometown, because their father, Archie, used to play for the Saints. Think a Manning vs. Manning matchup for the championship in the Big Easy might garner attention?

Manning-to-Denver also would create a fascinating dynamic with Tebow, only months after he was the focus of the NFL regular season and perhaps the most talked-about athlete in sports, a polarizing figure both because of his style of play - as far as possible from a classic, dropback passer - and his outspoken religious beliefs.

After taking over a struggling team, Tebow led the Broncos to comeback victory after comeback victory, struggling for three quarters before starring in the fourth quarter and overtime. With an offense transformed into a spread option attack built on Tebow's running, and a strong defense that kept games close, the Broncos won the AFC West title.

Tebowmania reached its apex in the playoffs, when he threw an 80-yard touchdown pass on the very first play of overtime to beat the Pittsburgh Steelers. The next week, though, Tebow was smothered by the New England Patriots, who easily eliminated the Broncos 45-10.

A little more than two months later, Tebow could be on the trading block.

That's not the only domino which could fall now that the offseason's biggest free agency question is seemingly settled.

San Francisco could decide to keep its own free-agent QB, Alex Smith, who went to Miami for a visit with the Dolphins after the 49ers' flirtation with Manning became public. If Smith does go back to the Niners, perhaps Miami will look to trade for Tebow, who played in college at Florida. The Titans, meanwhile, probably will stick with grooming Jake Locker, who was a first-round draft pick a year ago.

Denver, meanwhile, could try to give Manning some new targets, because they still have millions of dollars in salary-cap space available. The Broncos did not exactly have a wealth of wideouts last season, other than Demaryius Thomas, and they lost Eddie Royal to the San Diego Chargers as a free agent.

One of the greatest advantages of Manning coming to Colorado is the anticipated economic impact it could have.

"The main thing for the Broncos - it will mean is a big surge in revenue at the pro-shop probably right away," said CU Denver Professor Kyle Hurst. "As well as excitement if the Broncos are able to stay competitive, looking forward to the playoffs next year, and maybe the year beyond, advancing in the playoffs further than they did this past season. That would be a big jump in revenue for them."

"What you also have to remember about Tebow is: he's only a $1.1-million investment - that's his salary for 2012 - versus Manning which is $17 to $19 million. So, it's a lot less to recover," Darren Rovell, CNBC Sports Business Reporter, told 9NEWS Monday.

Rovell saysthe deal might mean a bigger payout for Tebow in the end.

"There really is not that much difference between Peyton Manning and Tim Tebow from a money standpoint. In fact, from the things that are unauthorized, which are unlicensed, I think you'll get more Tebow stuff than Manning stuff," he said."I don't think fans really care - they want to win. And maybe they thought that Tebow didn't help them get there - even though that great playoff win and what he was able to do to turn around the team - they think Peyton is real and that makes a difference. But from a dollars-and-cents-standpoint, where Tim Tebow goes - if he goes - is a much bigger business story than what Peyton Manning can do for Denver."

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Simone VonRivenburgh contributed to this report.