Phoenix chief executive Tony Pignata said the loss of Barbarouses was disappointing for the club but added that Phoenix officials backed the player's rationale.

"We offered Costa a two-year deal to remain at Phoenix but we understand that, given we have no youth league set-up, he wanted the opportunity to play more regular football," he said.

"The youth league component is vital for us and for football in New Zealand, but it has proven difficult for us to develop a way in which we can give our young talent the opportunity to shine. Unless something changes soon, it will be very difficult for us at Phoenix to bring young talent through and that would be a huge shame.

"We definitely need a youth league or reserves set-up and we've been working hard with New Zealand Football for quite some time to arrange something. If we can't sort something out we will continue to lose young talent like Costa because there is no vital stepping stone in that professional career pathway."

However, Pignata hoped Barbarouses would benefit from the shift to Brisbane.

"Whether he plays in the first team or not he'll get regular football in the National Youth League, which is a very good competition. He's a 20-year-old guy who wants to play, so the offer from Roar was an attractive one for him," he said.

"Costa was a foundation member of the club and has won a lot of fans in New Zealand. We wish him all the best for the future and we'll continue to watch his development closely."

Barbarouses said the prospect of linking with Ange Postecoglou's squad was an exciting one and an opportunity he was planning to make the most of.

"It's a time in my career where I have to get out of the comfort zone and really give myself a challenge," Barbarouses said.

"These next few years with Brisbane will be really crucial for my career leading into the most crucial years of the early 20s. I'm leaving my hometown club and I'm really excited for the challenge ahead with Roar.

"I think we can do something special with the team that's being built there."

Postecoglou said he believed Barbarouses would be a perfect fit for the squad he is building and said he would more than have the opportunity to cement himself in the club's A-League squad.

"I think he fits in with the style of football we want to play," Postecoglou said. "He's quick, exciting at an age where he really wants to break through and make a name for himself.

"We don't have his type of striker at the club, when you have a look at what we have with Reinaldo and Sergio (van Dijk), they are big strong strikers.

"Costa will give us that variety and we've already shown that if young players are good enough we'll play them."

The 20-year-old said leaving his hometown club would be difficult, but the keen interest shown by Roar to secure his services had persuaded him it was the right decision.

"As soon as I was looking around they were keen to have me and like I said, I like the direction the club is heading in," he added.

"(Ange) already has a couple of good strikers in Sergio and Reinaldo, but I feel I can offer something different up top with my speed and working off the target players.

"I think there could be some good combinations there."

Despite limited game time this season, the young striker scored against Sydney in November with a volley over Clint Bolton and has two assists to his credit.

Barbarouses has represented New Zealand at under-17 - where he captained his country at the 2007 World Cup tournament in Korea - under-20 and under-23 levels.