Nelly went from 0 to 100 really quick ... after being pelted in the head at a club in Miami.
An eyewitness tells TMZ ... the "Hot in Herre" rapper was hanging inside E11EVEN Miami, Friday night ... when he got whacked in the head with an object.
Check out the video ... you see the object -- possibly an ice cube -- tossed by someone on the balcony. You then see Nelly triggered ... ready to confront the culprit.
Nelly grabs the back of his head and peers up ... before charging toward the balcony.
Nelly's entourage and club security stepped in and prevented the situation from escalating. He was still able to enjoy the night ... once things cooled down.
The rapper ended by doing a short performance ... rapping throwback hits onstage.
There were no slaps, no cops ... just another night in the club.