Shirtless Fan Runs Wild On Field

A tight MLB game on Wednesday got a whole lot more interesting in the later innings ... when a topless fan ran onto the field, and, for a while, evaded security guards like an NFL running back.

The moment just happened in the Braves vs. Brewers game in Milwaukee.

Video shot by spectators inside the stadium shows a fan ripped off his shirt and made it down to the field, and then began dancing in center.

The guy shook his booty for quite a while before security eventually realized he was there -- and then, he evaded the guards who were trying to take him down for several seconds.

The man then sprinted from the outfield to the mound, before eventually making it to homeplate ... all while juking…