Roar have lost their last three A-League encounters yet sit just one point out of the top six, but Postecoglou believes they need to win back their confidence if they're going to make the finals.

"We got caught with the goal and unfortunately that's the rut were going through at the moment where we are just lacking a lot of confidence...as soon as the goal went in we dropped our level," Postecoglou said.

"We thought it was a pretty good first half, we were solid, they didn't really threaten us at all."

After a goalless opening half, the Jets returned fire with two goals early in the second stanza to blow Brisbane out of the water.

Postecoglou added: "We're lacking a lot of confidence and soon as the goal went in we dropped our level.

"It was a disappointing day and a disappointing result."

On the positive side, Brisbane's new Belgian signing Pieter Collen made his debut for the club but admitted it wasn't the ideal start to life in Queensland although he remained optimistic they could turn it around.

Collen said: "We have to pick up the good things and keep confident and keep working and that's the only way to get there."