The Sky Blues, who finished their 2011 AFC Champions League campaign this week, have not re-signed 20-year-old Danning along with Stephan Keller, Brendan Gan and Stuart Musialik.

The departure of Ghana-born Young Socceroo Danning is arguably the biggest though, considering the way he burst onto the scene in early 2009, scoring a winner against Wellington Phoenix in one of his first games for the club.

Sydney boss Vitezslav Lavicka told The Daily Telegraph that Danning's development hadn't come along as hoped.

"But he did have a serious injury (knee) and it has been very slow," Lavicka said.

"I spoke to Kofi and it is his decision to play somewhere else, possibly Brisbane.”

Danning made 22 appearances for the Sky Blues and scored three goals.

Lavicka also said Brendan Gan's development hadn't been sufficient enough to warrant a new deal.

The Sky Blues boss added Keller would head overseas while the club couldn't agree to terms with Musialik and may also head abroad.

"Both players have done a great job for us, especially the previous season," Lavicka said.

"We did offer Stuey a contract earlier but he declined. He may go overseas.”