"The performance that Rob had at Wanganui happened to be at the right time.
"We pitched the idea [of a title match]."
Oosthuizen, 27, another southpaw, has moved in similar circles to Berridge.
He also won the IBO Super middleweight title and made several defences including against ranked Australian Serge Yannick in 2012, whom Berridge knocked out a year later to signal his arrival on the world stage.
Osthuizen then won the vacant IBO light heavyweight belt by split decision against countryman Ryno Liebenberg (16-2) on March 14, and last month signed with a promotion run by top American manager Al Haymon, who includes Floyd 'Money' Mayweather among his clients.
"He is very tall, a little bit different as a boxer to other tall fighters - not as technical," said Kovacevic.
While the IBO is one of the lightly regarded bodies which sanctions world titles, Oosthuizen is still ranked 11th in the world by the independent website BoxRec, which signals a massive opportunity for Berridge, who is 34th.
Kovacevic said the quick turnaround to prepare for a different opponent should not be a problem as Powdrill also had a height advantage over Berridge so they were already getting ready for that kind of fight.
"We were in a mental state to do that [and] we were planning to be fit.
"That's two points we don't have to worry about.
"We strive for this, we're professionals, and this is what we do."
The last New Zealander to fight for a world title was Shane Cameron in his unsuccessful challenge to Australia's IBO cruiserweight champion Danny Green in 2012.
If Berridge can claim the world title, his management are already considering a fight being held in Wanganui after the success of Rise of the Fallen, which attracted a crowd of around 1000 to Springvale Stadium.
"The plan is to go over there and bring it back and then defend it in Wanganui - that's no joke," Kovacevic said.
"Rob was impressed with Wanganui."
His cousin, Rise of the Fallen promotor Paul Berridge, said he will definitely be going to South Africa along with Kovacevic, wanting to have the entire Team Berridge support team there after they missed last year's big fight in America against Vasily Lepikhin - a devastating stoppage defeat.
"There's massive things - huge things ahead from this fight [for Wanganui].
"If all parties come to the table, in saying that."