It may be week one of the preseason, but Rams and Cowboys fans are in midseason form ... 'cause loyal supporters of the organizations went toe-to-toe in a bloody brawl outside SoFi Stadium.
The fight went down right outside the SoFi gates in Los Angeles ... where video shows a fan wearing an Aaron Donald jersey getting thrown to the ground by a guy rockin' Troy Aikman threads -- before delivering some big blows to the head of the guy on the ground who appears to be out cold.