Headbutts Teammate After Shocking W

Baker Mayfields Rams debut had a Hollywood ending -- he led L.A. to a come-from-behind victory in improbable fashion over the Raiders on "Thursday Night Football."

Mayfield and the Rams were down early and went into the half trailing Las Vegas, 13-3.

But, with a few minutes left in the 4th quarter, Mayfield, down 16-3, took a page out of Tom Bradys book, erasing a 13-point deficit ... just as TB12 did against the Saints on "Monday Night Football."

With 15 seconds left in the game, Baker connected with wide receiver Van Jefferson for the game-winning touchdown, capping off an eight-play, 98-yard drive.

Naturally, Mayfield was pumped over the W ... and cameras captured him headbutting his teammate, defensive back Robert Rochell on the sideline out of excitement.

After the game, head coach Sean McVay gave Baker a game ball for his performance ... before turning over the floor to the 27-year-old for a victory speech.

"Good f***ing job, man, thats the way to fight to the f***ing end," Mayfield said after his teammates mobbed him in the middle of the locker room. "Im happy to be home, man."

Baker is now on his third NFL team -- after stops in Cleveland and Carolina failed to work out -- and theres no telling what his future in L.A. holds ... but whatever happens, this was a helluva way to start, and a game that wont soon be forgotten by Rams fans and players.