When asked about Brees likely taking the No. 1 spot during the 2018 season by Jeff Duncan of the Times-Picayune, Manning heaped praise on the veteran signal-caller: "I don't think it's a matter of if [Brees breaks the record], it's just a matter of when. He deserves it. He's been a great player for a long time."
Brees is just 1,495 yards behind Manning's record mark of 71,940 passing yards, which means he should surpass Manning during the early part of the season provided he remains healthy.
The 39-year-old Brees is set to enter his 18th NFL season, and it will be his 13th with the Saints.
Manning is impressed with his longevity, saying, "Obviously, he's just been the ultimate pro, taking care of himself, being in great shape. Credit to him for playing as long as he has at such a high level. ... He's just been a great model of consistency, what he and [Saints head coach] Sean [Payton] have been able to do together for (12) years now."
Like Brees, Manning spent 18 years in the NFL, but he retired following the 2015 season on the heels of winning the Super Bowl with the Denver Broncos.
Manning has Brees beat thus far with two Super Bowl victories to one, but Brees got the better of him from a head-to-head perspective.
When Manning was a member of the Indianapolis Colts, Brees and the Saints defeated them 31-17 in Super Bowl XLIV in 2010.
Brees was named the MVP of that game after completing 32 of his 39 attempts for 288 yards and two touchdowns.
That marked the first (and only) Super Bowl win in franchise history for the Saints.
Once Brees takes the passing yardage record, he will likely set his sights on another all-time mark held by Manning.
Manning is the all-time leader in passing touchdowns with 539, while Brees is tied for third at 488 with New England Patriots quarterback Tom Brady.
Brees will almost certainly need at least two seasons to reach Manning's record in that category, but with Brady showing no signs of slowing down at 40 years of age, it could be a battle to the finish between them.