SAN FRANCISCO - Whether he wins or loses on Sunday, Peyton Manning has already assured himself a place in American football's pantheon of greats.
Denver Broncos quarterback Peyton Manning, 39, faced a bleak future in 2011 when neck surgeries left him struggling to throw properly, forcing him to miss the entire season with the Indianapolis Colts, who eventually cut him in March 2012
But if the veteran Denver Broncos quarterback manages to mastermind an upset over the Carolina Panthers in Super Bowl 50 it will be the crowning achievement of a career that once looked to be in terminal decline.
Manning, 39, faced a bleak future in 2011 when neck surgeries left him struggling to throw properly, forcing him to miss the entire season with the Indianapolis Colts, who eventually cut him in March 2012.
Yet Manning went on to relaunch his career successfully with the Broncos, enjoying a vintage season to lead Denver to the Super Bowl in 2014, where they lost heavily to the Seattle Seahawks.
This season Manning has fought through adversity once more to reach his fourth Super Bowl, where he is chasing a second championship ring to book-end the one he collected with the Colts in 2007.
The nadir of a rollercoaster season came in November when he produced a career-worst performance in a defeat to Kansas City, featuring just five completions for 35 yards and four interceptions.
Manning was benched for the first time in his career thereafter, losing his place to deputy Brock Osweiler.
But a refreshed Manning returned for the play-offs and rewarded head coach Gary Kubiak by piloting the team through wins over Pittsburgh and New England.
"There is no question it's important to me, it's very personal to me," Manning said this week when asked to reflect on his tumultuous season. "No question this season has had some unique challenges."
Just 46 days shy of his 40th birthday, Manning will be the oldest starting Super Bowl quarterback in history when he takes to the field at Levi's Stadium in Santa Clara on Sunday.
- Farewell appearance? -
Many pundits believe it could be Manning's farewell appearance after 18 years in the NFL which have seen him accumulate more passing yards than any other quarterback.
That speculation intensified after his comment to New England coach Bill Belichick in the AFC title game that it "might be my last rodeo."
Manning has consistently batted away questions about his retirement, insisting that no decision has been made. "I haven't made my mind up and I don't see myself making a decision until after the season," Manning said on Monday.
Talk of Manning's retirement invariably invites discussion of his place in the pecking order of great quarterbacks.
Many rank him behind the likes of Tom Brady and Joe Montana on the basis of superior Super Bowl wins (four each) compared to Manning's lone victory nine years ago.
In the words of former Dallas Cowboys Hall of Fame Receiver Michael Irvin this week: "He's gonna need more than one Super Bowl victory."
Yet others reject the idea that Manning needs a second Super Bowl win to cement his place in the annals of the game.
"This is not a make-or-break game for Peyton. His legacy is already set," said the Denver Broncos general manager John Elway.
"He's already going to go down as one of the greatest players to ever play the game so if anything, this will do is just add to that legacy."
Not surprisingly, Manning's younger sibling Eli, a two-time Super Bowl-winner with the New York Giants, agreed.
"Honestly, I think there's maybe too much placed on rings and Super Bowl championships, because it's not one player," Eli Manning said.
"The quarterback is not the sole reason that you win a championship. Peyton, his impact on the game of football, will not be determined based off this one game.
"I hope he can win, but his impact has already been made."