The Austrian marksman posted a heartfelt message to the fans of what he described as 'Australia's biggest club', claiming that the club's management took issue with his international duties for the upcoming season and pulled an offer which Janko said he was willing to accept.

@JankoMarc & @SydneyFC part ways on good terms, thanks for everything did for us Marc #SkyBlueHero #RecordBreaker http://t.co/Np42vKu6Kq— Alex Wain (@alexwain) May 24, 2015

Janko, 31, is currently the captain of his native Austria who are in the thick of a qualifying race for the 2016 European Championships in France - and they look good value to appear at the tournament, currently topping a qualification group featuring France and Russia among others.

"Marc has done very well this season and we were happy with his performances and his contribution to Sydney FC," said Head Coach Graham Arnold.

"However he will miss a number of A-league games next season due to international duty with no FIFA breaks in the A-League. Add that to our busier schedule, including Asian Champions League commitments and after lengthy consideration we have come to this decision."

Despite his one year in the A-League, Janko was voted into Sydney FC's team of the decade, despite only appearing in one season for the Sky Blues. 

There's three international windows during the next #aleague season and only two are for competitive games (Oct and Nov). I'm suspicious.— Neil Sherwin (@neilsherwin) May 24, 2015

He became the first Sydney FC player to claim the A-League's Golden Boot, notching 16 goals - leaving him in fifth place on Sydney's all-time scorers list, behind current captain Alex Brosque, Alessandro Del Piero, Steve Corica and Mark Bridge.

It has not been all bad news on the player-retention front for Sydney though, with Jacques Faty and Mickael Tavares re-signing and the club still hopeful of securing the signature of midfielder Milos Dimitrijevic.

The news comes a week after Sydney's disappointing performance in the A-League grand final, losing 3-0 to rivals Melbourne Victory.

It appears the club and player will leave on good terms, with Graham Arnold wishing Janko all the best.

"On behalf of the club and the team I'd like to thank Marc for his service and the professional way in which he has conducted his business. We wish him and Austria all the best for the future."