Travis Kelce Catches Wild, Behind the Back Pass From Patrick Mahomes

Travis Kelce and Patrick Mahomes look in midseason form already ... 'cause the two just connected on a crazy behind the back pass.

The play happened just moments ago during the Lions vs Chiefs preseason game ... on third down with three yards to go, Mahomes scrambled to his right -- before flicking the ball toward his main receiving threat.

TK's able to get the first down and more ... ending up just inside the Lions' 25-year-line -- a nice little chunk of yardage from one of the weirdest plays we'll probably see this preseason.

Tons of football fans -- including Trav's big bro Jason Kelce -- loved the play ... but, don't imagine the two did this on a whim ... 'cause Pat and Trav have been quite open about wanting to make this happen.

Mahomes joined "First Things First" on FS1 just a couple months ago ... talking about when exactly he was going to make the play like he previously told them he would.

PM took all the blame for not executing it last season ... 'cause he says Head Coach Andy Reid's been onboard for years -- so he could've done it just about any time he wanted.

Pat and Travis are getting ready for the regular season -- set to kickoff for them on September 5 against the Ravens -- and, they're back in Kansas City together after months of vacation.

Killa Trav's been globetrotting with his GF Taylor Swift ... who couldn't make it to Saturday's preseason game since she's in the middle of a show at Wembley Stadium in England.