Warren Moon Says Eli Manning Is a Hall of Famer, He Has 2 Rings!!

If Eli Manning never plays another down in the NFL, his next stop is Canton ... so says Warren Moon, who tells TMZ Sports the NY Giants QB is 100% a Hall of Famer.

The G-Men just announced Manning will ride the pine as rookie Daniel Jones takes over as the starter in Week 3 ... sparking debate over whether Eli will be considered among the all-time greats when he calls it a career.

Moon -- who was inducted into the Hall in 2006 -- says they better start getting Manning's jacket measurements now ... 'cause there's no way he WON'T get in.

"I think he is based off his numbers and what he's able to do as a team as well," Moon told the fellas on the TMZ Sports TV show, airing Tuesday night on FS1.

"He's definitely put together a career that's Hall of Fame worthy."

FYI -- Manning's 8th in all-time TDs passed (362) and 7th in passing yards (56,537). And, oh yeah ... 2 Super Bowls don't hurt either.

"I've just looked at his body of work ... and he's won the championships, which is something very important to the voters when you go into that room," Moon adds.

"He's got 2 of them and he was the MVP in both of those games. That's gonna bode well for him."