Favre holds the record with 508, a feat accomplished from 1992 to 2010.
Now that the 37-year-old Manning needs only 66 touchdown passes to break the record, it's an appropriate time to examine if we should expect him to get to 509 and when it will happen.
Here's a breakdown of Manning's career touchdown efficiency:
Based on that information, Manning would need to play in 34 more games and attempt 1,667 more passes to reach 509 career touchdown strikes.
At that expected pace, Manning would have to play until Week 3 of the 2015 season and average 34.3 attempts per game until then.
Is the latter out of the question?
Manning has averaged 34.8 attempts per game since entering the NFL in 1998 with the Indianapolis Colts. Outside of the entire 2011 season, the former No. 1 overall pick hasn't missed a game in his career.
The length of his contract won't be an issue, either, as he's signed with the Broncos through the 2016 season.
In Week 3 of the 2015 season, likely sometime in late September, Manning would be 39 years old, which isn't a ridiculous age to expect him to still be able to be productive in the NFL.
Remember, Favre called it quits for good at 41. Johnny Unitas was 40. Dan Marino, John Elway and Fran Tarkenton retired at 38. Heck, Warren Moon was 44 when his professional football career ended.
Even factoring in a late-career decline from Manning—after his seven-touchdown performance, expecting a regression from Manning is somewhat unfathomable—he still should break Favre's touchdown record at some point during the 2015 campaign.
Manning will play in 47 more regular-season games until the end of that season.
Here are the averages Manning would need to maintain over that stretch to get to 509:
With those "extra" games, Manning could afford to see his career touchdown per game average drop more than a half a touchdown. Also, he could throw the ball four fewer times per game and would only need four more attempts per each touchdown thrown.
So, at his current Hall of Fame worthy pace, Manning should get to 509 career touchdown passes before October in 2015. If his efficiency worsens as he nears his 40th birthday, breaking the record during the last game of the 2015 campaign is undoubtedly achievable.
Will Peyton Manning break Brett Favre's career touchdown record of 508?