Tom Brady and Peyton Manning may be close friends off the field but both remain competitive, even at their ripe old ages of 38 and 39. In fact, the Patriots quarterback thinks Manning has two years left in his NFL career while Brady says he's good for at least seven more.

We know this thanks to emails Brady sent a friend during the 2014 season. These emails were submitted among documents in the NFLPA's suit over the four-game suspension for Brady's role in Deflategate.

On Nov. 1, 2014, six days before the Patriots rolled the Broncos, 43-21, Brady wrote to childhood friend Kevin Brady, "Thanks popa, I've got another 7 or 8 years. He has 2. That's the final chapter. Game on."

Brady's email was in response to a Grantland story about the decline of Manning compared to Brady.

(Related: We wrote about Manning's relative decline last month.)

"I've got another 7 or 8 years, He has 2" is innocuous enough. And maybe Brady has the benefit of actually talking to Manning about his future. Or maybe he's just speculating off the cuff while responding to a friend. In fact, days before sending this email, Brady said this publicly about Manning ahead of their matchup.

"[Manning has] been one of the greatest players to ever play," Brady said. "I've been fortunate to share a field with one of the best players that has ever played the game. And every time we play a Peyton Manning-led team, it comes down to the wire. Everything is usually at stake."

Meanwhile, another email exchange dated Nov. 3, 2014, between Brady and blogger friend Jay Flannelly, includes the typical sycophantic observations from the fan with the even more typical Patriots-esque response from Brady.

Flannelly writes: "LOL front runners LOL. Manning needs things to be perfect to succeed, weather, his system, etc. You right about November -- HUGE. ... Also agree with your postgame presser assessment--- left points on the field -- should have put a hundred on that team...FGs into TDs changes that--finnish drives.

"Always helps when other team is DUMB -- LBer on Gronk on 2 yd line? VON MILLER!? I really like this team and we have a long way to go but I want ring 4! Rest, rehab, reflect -- Lets get ready for this run. "Proud of U ... GO BLUE!!! GO PATS!!! GO TB!!! GO G!!!

Brady wrote back, "We are some hard working grinders beav. That's what our team is all about. Our best is still ahead of us."

So there you go. Using Brady Math, the Pats quarterback will play until he's 45 or 46 while Manning will be done next season. Unfortunately, the Pats and Broncos aren't scheduled to meet again until 2017 -- unless, of course, it's in the playoffs.

Brady and Manning have been rivals and friends for some 15 years. (USATSI)
Brady and Manning have been rivals -- and friends -- for some 15 years. (USATSI)