Shaq Diesel just responded to LaVar Ball a la Tupac -- with a brand new killer 3 minute diss track going right after the Big Baller.

O'Neal's flow is straight fire over a classic Jay-Z beat -- and he mocks LaVar's basketball career right off the bat.

"I been doing this a long time ... when you were averaging 2 points riding the pine."

There's more ... Shaq also responds to LaVar's claim that he could beat him in 1-on-1.

"You having a dream and when you wake up apologize. And bow down to my Staples Center statue hanging off the side (of the building)."

But there's a twist ... with Shaq giving LaVar props for his parenting skills at the end of the track -- plus, he praises LaMelo's jump shot.

Enjoy ... and let's pray LaVar responds.