NFL football quarterback Peyton Manning, center, takes a tour with executive vice president of football operations for the Denver Broncos John Elway and Broncos coach John Fox at the Broncos' training facility in Englewood, Colo., Friday, March 9, 2012. Four-time MVP Manning opened his free-agency tour of NFL suitors Friday. (AP Photo/The Denver Post, John Leyba)

DENVER - Peyton Manning is negotiating to join the Denver Broncos, ESPN reported Monday.

Citing anonymous sources, ESPN said that 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 the trade of Tim Tebow, who energized the Broncos in leading them to the playoffs last season despite his uneven play.

The San Francisco 49ers and the Tennessee Titans have been the other teams considered finalists in the race to sign Manning.

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 Tennessee Titans, San Francisco 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 reportedly 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.

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 oustpoken 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.