Popovic had been tipped to take over at Sydney, at least temporarily, if head coach Lavicka was given the chop mid-season following his dismal run of results.

But after an upturn in the club's fortunes, Lavicka - who took Sydney to the double last season - was given the chance to prove himself again at the looming Asian Champions League.

Now Popovic has revealed he will be quitting Sydney to take a similar role at the club where he was former skipper during his five years at Palace between 2001 and 2006.

The club says Popovic - a former captain at Sydney too until he retired mid-season in 2008 after joining them the previous year from Qatar side Al-Arabi - will remain with the side until all hope of making the finals is exhausted.

“Tony has been a loyal servant to both Crystal Palace and Sydney FC. He is highly regarded around the world and has been a great asset to our club,” Vice Chairman Scott Barlow said.

“Sydney FC has helped Tony to develop quickly. He is one of Australia’s most talented up-and-coming coaches. This has been clearly recognised by Crystal Palace.

“We consider this as a fantastic next step for Tony and we wish him well in his further development. We are confident that he will benefit from the overseas experience so that we may one day welcome him back to Sydney FC.

“With Tony returning to Crystal Palace it strengthens our already good relationship with the club. They were very cooperative when we signed Nick Carle last year.”

Popovic played 123 games for Crystal Palace between 2001 and 2006 where he was an integral part of the team's defence and became club captain.

He returned to Australian football in 2007, joining Sydney FC where he was immediately installed as captain. After 19 appearances he announced his retirement before immediately taking up an assistant coaching role with Sydney FC, a position he has since held.

“I have thoroughly enjoyed my time at Sydney FC as both a player and assistant coach. I have learnt a lot and working under Vitja for the past two years has been excellent for me. I will remember very fondly what we achieved in the A-League last season,” Popovic said.

“This is a great opportunity for me. It will help me further enhance my skill set as I work hard towards becoming the best coach I can be.”

Hyundai A-League Championship winning coach Vitezslav Lavicka said Popovic was a true professional.

“Tony is a very good person, a true professional. He will have a long and successful future as a manager. It is sad for us but this is a great opportunity for him and I know he will do very well,” Lavicka said.

“We are very happy Tony is committed to stay with us and help us as we keep pushing to reach the A-League finals this season.”