The 39-year-old holds records for the most regular-season passing yards (71,940) and touchdowns (539) in a career, has won five MVP awards, is a 14-time Pro Bowler and is looking for his second Super Bowl win in four tries.
Whether that decision comes after Super Bowl 50 or in another year or two is up in the air. But according to NFL Network's Ian Rapoport (h/t Austin Knoblauch of NFL.com), Manning has confided in those closest to him that Denver's game against the Carolina Panthers on Feb. 7 will be his last.
"The reality is he let the cat out of the bag a little bit," Rapoport said. "I also know he has told close friends that he expects this to be his last game as well."
Manning spilled the beans after Denver defeated the New England Patriots on Jan. 24 in the AFC Championship Game, when NFL Network caught him talking to New England head coach Bill Belichick at midfield, per Michael David Smith of Pro Football Talk.
"This might be my last rodeo," Manning said.
Around the NFL reported Manning also told New England quarterback Tom Brady: "This could be it."
He must have emphasized "could," because Around the NFL later reported that Manning has not made up his mind:
Around The NFL @AroundTheNFL
Peyton Manning wouldn't say whether he plans to retire after Super Bowl. 'I don't know the answer to that question right now.'2/2/2016, 1:23:05 AM
It would not be shocking if Manning's 18th season was his last, considering foot and rib injuries hampered him toward the end of the year and forced him to miss six games. He had his worst season in 2015, with nine touchdowns, 17 interceptions and a quarterback rating of 67.9.
But Manning is one of the game's ultimate competitors, leading his team to the Super Bowl after he came off the bench in the second half of a Week 17 win against the San Diego Chargers. Ralph Vacchiano of the New York Daily News reported Manning's brother, New York Giants quarterback Eli Manning, said Peyton had not told him whether he'd made a decision on retirement.
It's possible the outcome of the game will dictate Peyton Manning's decision. If he loses, he'll still be a Hall of Famer, but he will be just 1-3 in Super Bowls, and it will be hard to consider him the greatest quarterback of his generation over Brady, who is 4-2 in Super Bowls.
If Manning wins, though, he can ride off into the sunset as a champion—just like another beloved Denver quarterback (John Elway) did.
Either way, it's been a heck of a career.