Hewitt becomes the first Kiwi to qualify for the world pro junior series and was only just settling back into life at Mount Maunganui after two months surfing, training and competing in the United States.
He said Callinan phoned him last Thursday giving him the heads up about his likely elevation. He missed the first event in Bali but is desperate to make up for lost time at Arpoador, a left-hand point break sandwiched between the iconic Copacabana and Ipanema beaches.
"I wasn't quite sure when Ryan called saying he was injured and didn't know whether to book a flight or not, but the official email came through on Thursday night so it was all on," he said before leaving on Sunday.
"Despite the rush, and the cost, I'm stoked to get the opportunity because the world junior series is the pinnacle."
Flights at such short notice cost $6000, with Backdoor surf shop, Burger Fuel and CNS Clinic all chipping in financially, although the irony is Hewitt has left without the backing of Aussie surf giant Billabong after he was dropped from their team the day before his final pro junior qualifier in South Australia because of the global economic downturn.
Hewitt signed with Billabong after finishing third at the ISA world junior champs in Portugal in 2007 and said his axing came out of the blue. With teams generally signing their surfers to a calendar year, Hewitt's search for a replacement backer has so far proved unfruitful.
"The timing was real bad, and apart from an email, I still haven't heard from anyone at Billabong.
"Financially, organising this trip to Brazil at such short notice without the financial backing or team support I would have got in the past hasn't been easy," Hewitt said.
"My boards (in Brazil) will be clean of a major sponsor for the first time and I'll definitely be the only one in the comp with no nose sponsor, but maybe it'll help me get noticed and get picked up by someone else," the 2009 national men's open champion said.
Hewitt will leave Brazil right after the pro junior, arriving back in New Zealand for a matter of hours before heading across the ditch to surf in the Kangaroo Island QS (qualifying series) event in South Australia.
The third leg of the world pro junior series is in Sydney next February, with Hewitt hopeful he'll do well enough in Brazil to stick around.