DENVER — When the four-time MVP with the four-time surgically repaired neck takes the field Sunday night for the Denver Broncos’ opener against the Pittsburgh Steelers, it will have been 1 year, 8 months and 2 days since Peyton Manning’s last meaningful snap.

What a long, strange journey it’s been.

Manning’s march began with an irritated nerve in his neck that got worse and eventually weakened his throwing arm, leading to a series of operations that forced him to miss all of the 2011 season.

Without him, the Indianapolis Colts nosedived and then decided to rebuild from top to bottom, including selecting Stanford quarterback Andrew Luck with the top pick in the draft.

So, they cut Manning loose on March 7, marking the end of an era, a 14-year alliance between the team that drafted him 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.

A thousand miles away, Denver was Tim Tebow’s turf. But management wasn’t completely sold on the exalted but erratic passer for whom coach John Fox had dusted off the old read-option offense last season.

Two weeks after he stood alongside Colts owner Jim Irsay at an emotional farewell news conference, Manning was standing next to John Elway, the powerful pair of Super Bowl winners talking about hoisting another Lombardi Trophy, this time together. And soon.

While that quest begins in earnest Sunday night, it had its roots in Denver long before Manning ever dreamed he’d be wearing the orange-mane mustang on his helmet instead of the horse shoe.

Shortly after signing with the Broncos, Manning visited Coors Field with wide receiver Eric Decker and revealed that he had worked out with his buddy, Rockies first baseman Todd Helton, during the NFL lockout last year.

While Manning, who unseated Helton as the starting quarterback at the University of Tennessee in the mid-1990s, was rehabbing from neck surgery, Helton helped arrange for him to use the Rockies’ facilities to work out.

“He’s a great friend,” Manning said that day at the ballpark. “What he did for me last year, allowing me to use this facility, use the trainers to work out as part of my rehab process. I’ve come a long way ... They were a big part of it. The whole Rockies organization, I can’t thank them enough for opening their doors to me last year when I certainly was an outsider. I’ll always be indebted to them.”

Manning’s right triceps had atrophied after one of his neck surgeries. He told the New York Times recently that when he went with Helton and a Rockies trainer to an indoor batting cage at Denver’s downtown ballpark, the first pass he threw to Helton nose-dived so much that Helton actually thought he was just goofing around.

He was dead serious. His arm was shot, his future in football in doubt.

A few days later, an MRI revealed that Manning needed spinal fusion surgery. Nobody realized it at the time, but Manning’s days in Indy were numbered.

Manning got stronger and stronger and by the time he left Indianapolis, he had a doctor’s note saying he was ready to return to work. He proved that in private workouts for several teams.