After announcing a flurry of signings, the loss of Brillante is a significant blow for the defending champions as they seek to retain their A-League crown.
Brillante was a key midfield cog alongside fellow Socceroo Brandon O’Neill over the past three seasons with the Sky Blues convinced he would be heading, if anywhere, to Asia.
However, it’s believed the 26-year-old has been swayed by a monster City contract - believed to be in the vicinity of $500,000 a season.
City, with Frenchman Erick Mombaerts unveiled as head coach only days ago, decided to act after the departure of Kearyn Baccus back to his homeland South Africa to join Kaiser Chiefs.
The industrious Brillante nearly signed for South Korean club Pohang Steelers earlier this year, but the deal fell through at the last minute.
Capped five times by his country, Brillante joined Serie A club Fiorentina back in 2014, for whom he made just two appearances before subsequent loan spells at Empoli and Como.
A return to the A-League followed, with the one time Gold Coast United and Newcastle Jets midfielder making 79 appearances for the Sky Blues before his contract expired at season’s end.