Don't stick a fork in Eli Manning just yet -- his friend and ex-teammate, Plaxico Burress, is adamant he'll play again in 2020 ... telling us, "It won't be the last you see of him."
Plax LOVED the way 38-year-old Eli played against the Philadelphia Eagles this weekend -- "S**t, I think E-Money held his own!"
And, while most people think Eli will hang it up at the end of the season, the former NY Giants WR says he just ain't convinced Manning's ready to retire.
"I don't think it's the end of the road. That's my main man. That's my homeboy," Plax says ... "It won't be the last you see of him. I'll tell you that."
The big question ... will Eli stay with the Giants, where he's played his entire career or move on to another team in need of a QB.
When Manning DOES decide to retire, Plaxico says there's ZERO DOUBT he'll end up in the Hall of Fame.
"First ballot, no doubt about it," Plax says ... "How is he not? 2 Super Bowls, 2 MVPs ... how many QBs have done it?"
Plaxico played with Eli on the Giants from 2005 to 2008 -- and caught the game-winning TD in Super Bowl XLII.