8:54 PM PT -- A rep for Penn just released the following statement in an attempt to clarify what happened before cameras started rolling ... telling TMZ Sports, "Upon meeting friends for a concert at the Lava Shack, words were exchanged between BJ and the acquaintance. From witness accounts, BJ tried multiple times to defuse the situation, but was hit repeatedly and knocked to the ground, as seen on the video."
The rep continues, "When he got back up he was disoriented, yet realized how serious the situation and threat was and felt there was a need to defend himself. We are thankful that BJ nor the acquaintance were not seriously injured.”
12:17 PM PT -- We spoke with someone very close to Penn who tells us BJ felt the other guy had been following him around and trying to bait him into a fight ... saying, "This guy is notorious for taunting BJ."
Our Penn source says ... after getting knocked to the ground, BJ was disoriented and his response was to go after the guy. And, that's what you saw in the original video.
11:48 AM PT -- TMZ Sports has obtained new footage showing BJ Penn getting knocked out when the fight spilled into the street.
You can see Penn egging the other guy on -- the same guy from our first video -- and when BJ's opponent throws a left hook, it connects flush with Penn's chin, sending him crumpling to the ground, arms sprawled.
BJ's friends immediately help him back to his feet -- and a screaming match ensues between all of the bystanders.
We're told the knockout in the street came FIRST. And, later on, BJ reengaged, tackling the guy from behind and knocking him down.
We spoke to the other combatant who tells us he was hit with a "cheap shot" and that's why Penn was able to mount him. But, when they squared up face to face, BJ went down.
UFC legend BJ Penn was involved in another bar fight in Hawaii -- this time, the 40-year-old was sprawled out on top of another man raining down punches, and TMZ Sports has the video.
Penn was at the Lava Shack on the Big Island on Tuesday when he got into it with another dude -- and in classic Penn fashion, the fight ended up on the ground. We have a pic of Penn at the bar earlier in the night. You can see the clothing is the same.
Penn had his opponent mounted -- and his legs were hooked in -- and he threw at least 4 ferocious shots to the other man's head ... and it looks like all of the shots landed pretty clean.
You can see several men in red "Security" shirts move in and try to break the whole thing up.
Unclear what started the fight -- but we're told law enforcement responded to the scene. It does NOT appear Penn was arrested and cops say they have no record so far.
The situation is similar to a fight Penn got into back in June on Oahu -- where he pummeled a man outside of a strip club while a group of people looked on.
Cops were called to that incident as well -- but again, Penn was NOT arrested or charged with a crime.
We reached out to Penn's camp for comment -- so far, no word back.
Penn is slated to fight Nik Lentz in the near future but no date has been set. Dana White has said the fight will be the last of Penn's legendary career.