understands the four-year deal is signed, sealed and delivered after the Serie A club made an offer in recent weeks. 

Negotiations were conducted between the two clubs as well as Antonis’s father Peter before the deal was inked in recent days. 

Antonis, 19, who was called up to the Socceroos late last year, is set to remain in Australia till his commitments are over with the Young Socceroos at the FIFA Youth World Cup in Turkey this July.

This is a blow to Sydney FC's plans for next season but shows the level of interest in the club from Italy since the arrival of Sky Blue marquee Alessandro Del Piero. 

Antonis is set to train with the Young Socceroos next week on the Central Coast as part of the national team’s preparations for the youth World Cup. 

The news comes hot on the heels of Melbourne Heart's Eli Babalj's move to AZ Alkmaar also on a four-year deal after the two clubs and the player agreed terms overnight.

Babalj travelled to the Netherlands to undergo a medical and resolve personal terms after AZ scouts visited Melbourne this year to watch him play at Melbourne Heart.