Some call it a video game simulation, Matt Barnes calls it a preview of real life.
The NBA star tells TMZ Sports he's seen the UFC video game brawl between him and Derek Fisher -- and says the way he whooped D-Fish's ass in the game is EXACTLY how it would go down for real.
"My kids showed me that," Barnes says ... "That's what would really happen if it came down it it."
Barnes also told us he doesn't need an octogon -- he'll fight Fisher anywhere.
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