12:56 PM PT -- Shawne Merriman says now that the Rivers ride is officially over ... his next stop should 100 percent be in Canton, Ohio.
Rivers' former teammate tells TMZ Sports there's "no question" the Chargers legend should be in the Hall of Fame one day.
"Phillip Rivers is a Hall of Famer and anyone who look at the numbers can tell," Merriman says. "You would have liked for him to have a Super Bowl or two up in there to make it official but anybody who don't think Phillip Rivers is not a Hall of Famer has just bumped their heads."
Merriman also praised Rivers for being a hell of a teammate ... telling us the guy was "so damn competitive."
"I never played with anybody who was as competitive as Phillip was and it showed on the field," Merriman said.
Philip Riversis done with the NFL ... the Indianapolis Colts star quarterback announced Wednesday he's retiring after 17 seasons.
Rivers ends his career with a super impressive resume ... he made 8 total Pro Bowls, threw for more than 63,000 passing yards and logged 421 passing TDs.
In fact, some believe the work he put in with the Chargers could eventually one day earn him a bust at the Pro Football Hall of Fame.
As for why Rivers -- who had a solid season in his first year with the Indianapolis Colts in 2020-21 -- decided to finally call it quits, he said a growing desire to coach high school football helped him make the choice.