Two days after Suge Knight got his ass kicked in a hotel brawl, the former music mogul pled guilty to a completely different beatdown ... the one in which he allegedly chased (with his car), punched and kicked his girlfriend in the head.

As part of a deal in Las Vegas Justice Court, Suge pled guity to misdemeanor domestic battery in the assault on his girlfriend, for which he was arrested last year.

At the same time, however, Marion had two felony drug possession charges and one felony coercion charge stemming from the same arrest dismissed. Why?

Sources say the felony charges were dropped because cops can't find Melissa - who was the prosecution's main witness - according to the Las Vegas Sun.

Shady, to say the least. Suge was fined a whopping $340, has to complete 48 hours of community service and has to attend domestic violence counseling.

Suge Knight may have gotten his face bashed in twice in a nine-month span, but he's still bad ass enough to make his girlfriend mysteriously not show up in court.