Fletcher Cox If Eagles Play Chiefs in SB I Know Jason Kelce's Rooting For Philly!!!

Philadelphia roots are apparently thicker than blood in the Kelce household ... 'cause Fletcher Cox tells TMZ Sports he's sure Jason Kelce would cheer for the Eagles to beat Travis Kelce's Chiefs if they met in next month's Super Bowl.

A Philly showdown with Kansas City would happen if both teams pull out wins on Sunday ... and Fletcher is confident the Eagles will hold up their end of the bargain in a home tilt with the Commanders.

The former Birds D-lineman said he's expecting at least a 10-point victory ... although he did say he has big respect for Jayden Daniels and the rest of Dan Quinn's Washington team.

The Chiefs, of course, would then have to beat the Buffalo Bills at Arrowhead Stadium to make an Eagles vs. Travis matchup come to fruition ... but if it does, Cox is sure his famous ex-teammate would wear green for the big day.

"We know he's going with his team," Cox said with a big smile.

The dilemma has actually faced the Kelce bros. before ... you'll recall, Philadelphia and K.C. met in SB LVII -- but Jason was playing back then, so he didn't have any choice in the matter. In games since his retirement, Jason has been all for Travis -- wearing red throughout the tight end's playoff run last season.

No matter what goes down in the next few weeks -- Cox says he's glad he'll be in the stands for Sunday's NFC Championship Game either way ... explaining to us his body sure feels better on Mondays now that he's retired.

In addition to getting some much-needed rest, Cox is also spending some of his retirement time partnering with Colt ... assisting in the org.'s efforts to raise awareness for gun safety. In fact, he's helping spread the word about a sweepstakes Colt is running, where some winners can get some serious cash if there's a safety in the Super Bowl!