You better come correct if you challenge Jimmy Fallon to a rap battle ... 'cause Jimmy just put one of Post Malone's artists in a body bag.
The 'Tonight Show' host wasn't playing around when he went rhyme-for-rhyme with Post's upcoming artist, Tyla Yaweh ... hitting him where it hurts with no regard for human life.
It all went down at Paddy Reilly's Music Bar in NYC after Post's appearance on the 'Tonight Show', and ya gotta watch the video ... Jimmy GOES IN, Tyla flops hard and Post bows down.
No word on Jimmy's plans to drop a mixtape.