The action picked up in the second round as Papuni came forward and both men connected with hard hooks at the same time.
Papuni followed up with a good shot, then threw the pressing Berridge off him, with the referee warning the Wanganui southpaw about grappling.
Each man threw bombs and ducked out of range, with Papuni looking hurt by a Berridge body shot at the round's close.
Berridge is known as the diesel engine who starts slow but maintains a steady pace, and he was catching the lunging Papuni with counterpunches and hooks, but the tough Cantabrian was still there.
Papanui wailed away and did catch Berridge as the round ticked down, as Berridge had a slight slip and began bleeding from a cut on the eyelid.
To no one's surprise, a fourth round was called to find the winner.
Berridge started very well with his lead hand and then uppercuts, as Papuni tried to close in and fired off some up and downstairs combinations.
Yet Berridge still got through with clean counter punching left hooks and a body shots, before Papuni responded in the final minute with a solid straight hand and then hook of his own.
It still seemed to the commentary team that Berridge had done enough, like in the first fight, but to the No 1 seed's disappointment it was the Cantabrian who got his hand raised.
From both men's post-fight interviews, it appears a rematch is on the cards, under the traditional fight-length format.
"This challenge was a difficult one. Man, Robbie can hit, some power behind the shots," said Papuni.
"I came here to win. I think this was only a taste with what New Zealand can come up with.
"I think later we could make this a ten rounder."
Berridge seemed to be keen on that.
"Let's do it over - a ten round fight. This was a fun night, all respect for Reece."
While the decision may not have gone Berridge's way, perhaps he had been a little lucky to be tied on scorecards with underdog Falekaono earlier in the night, although 'the Butcher' conclusively won the fourth extension round.
The concern before the fight is how Berridge would handle the short format and Falekaono made the sprint work for him in round 1 as both men tied up a lot, and then the Tongan-Kiwi wobbled Berridge with a counter right hand, followed shortly after by a good body shot.
Falekaono moved in good angles to stay away from Berridge's heavy hands, moving with speed as neither man connected meaningfully in the second round, with the commentators feeling ranked outsider was poised for an upset.
Berridge started the third round with a straight left but could not follow up, before Falekaono got another great counterpunch.
But the veteran was beginning to find his pace as both men brawled, with Berridge connecting with a good left in the closing changes that busted Falekaono open.
While the commentators thought the Berridge rally had come too late, the judges did not agree, so the extension round was ordered.
Berridge now had his confidence and gave a textbook exhibition of grinding away, as a tired Falekaono had to absorb a lot of body shots, before being opened up further on the head.
With his superior conditioning, Berridge earned a clear unanimous decision for the extension round.
"He's a good fighter," Berridge said of his opponent afterwards.
"I took a couple of shots and that woke me up. Then it was game over."
